How to calculate the numbers of bags of cement in the foundation of a simple bungallow from a building plan.

A prospective client first question is an estimate to know the numbers of blocks and number of bags of cement required  to complete his building project.

But for this article I will write on calculating the numbers of bags of cement for a simple project of 2 bedroom bungalow. Using the plan shown below.


For this plan the total wall both internal and external is 72.5m all (check for the calculations )

Taking the thickness of block as 150mm or 6” the foundation base is taken as 150mm(or 0.15m x 3)=450mm or 0.45m or 18”.

Now for any concrete you want to calculate, first find out the volume.

For the foundation of the plan above

450mm(breadth) x 72.5m (entire length) x 150mm(foundation base thickness)=4.894m3

Now the volume of a bag of cement is given as 0.035m3 but lets use 0.03m3 to cater for shortages.

There are two major mixture ratio for concrete 1:2:4 or 1:3:6, there are others, but we are going to base our calculations on these two. 1:2:4 means one portion of cement is mixed with an equivalent volume or ratio of two of same portion of volume of cement in sharpsand and four of same portion of volume of cement in granite. That is, if I have a cement of 1m3, then I will need to mix it with 2m3 of sharpsand and 4m3 of granite stones. However one bag of cement is calculated to be approximately two headpans of sand or granite, therefore for one bag of cement in ratio 1:2:4, you will add four headpans of sharpsand, and eight headpans of granite, this is the standard , though experience has shown that materials properties varies, hence there is always little variations in quantities used on site.

Now, for the plan above, the numbers of bags of cement needed in the concrete is simply calculated by dividing the total volume of cement in concrete by a volume of one bag which is taken as 0.03.

For total volume of cement in ratio 1:2:4, add the numbers together,1+2+4=7

Divide the volume of concrete by 7 to get the volume of cement in concrete.

i.e 4.894/7=0.7m3 for volume of cement.

Remember  volume of one bag of cement is 0.03, then divide 0.7m3 by 0.03

=23 bags of cement

Also if the ratio is in 1:3:6, simply add 1+3+6=10

Divide volume of concrete by 10 to get the required volume of cement in concrete

i.e 4.894/10=0.4894 for volume of cement

Don’t forget we are taking the volume of one bag of cement as 0.03,

Then divide 0.4894m3 by 0.03m3

=16 bags of cement (this is most applicable on good and fairly stable soil.



An architect with decades of experience


  1. Are you saying that you need only 23bags for 4.894m3 of 1:2:4 concrete and 16bags for 1:3:6. Your mathematical approach suggests you are either an Architect or a Mathematician. You didn’t take care of the voids in the fine and coarse aggregates which will definitely increase the figures you quoted. If you are an Architect I will advise you concentrate on building plans which is your core competence. Going into building construction, structural design has the capability of increasing the incidence of building collpase

  2. I agree with Ogbonna, even by the “rule of thumb” of about 6 – 7 bags of cement/cub.m in concrete mix 1:2:4 you will not use less than 30 bags, ideally 35 bags.

  3. i have expected Ogbonna to create his own enlightenment forum instead of criticising a noble gesture. However, i appreciate your slightly partial response though

  4. u actually 4got to take care of waste that could result from concrete handling/placing, any way i did not expect much from a desperate architect, pls we dont want more collapse of buildings, try and talk more of building design, wishing u the all the best

  5. @Ogbonna and Etubi, I think you don’t need to fret yourselves so much, your contributions are highly appreciated.
    Yes I know by the rule of thumb standard 1:2:4=6.18 bags/m3 and 1:3:6=4.8 bags/m3 but as I have explained with the write ups
    (though experience has shown that materials properties varies, hence there is always little variations in quantities used on site.)
    The wastages aren’t measurable depends on the sizes and properties of the materials so is ignored.
    As for Etubi you are 100% correct I am very! very! desperate hahhahahah!! lol

  6. Thanks a lot Emmanuel. Pls don’t mind Ogbonna and Etubi, your point was well made and also covers the issues they raised. If only they were more patient to read and digest your point. For me I love what you’re doing. Keep at it.

  7. hmmm, i really appreciate you emma, atleast it makes those of us who do not have any idea of build tech to know certain things when dealing with contractors. so even if we are cheated it will not be much. thanks. Chima

  8. Well done, Emmanuel. Your write ups have been extremely beneficial, esplly for novices like me. I also thank the other contributors for adding value

  9. If only Etubi & Ogbona were 1/2 as decent as Ibrahim 2 hav jst made their point sensibly. ‘cuz a good engineer or an experienced site worker should know dat 4 wateva values given by calculatns, a percentage z given 4 wastage. Besides d calc by Emma waz by volume and voids r nt considered.

  10. If only Etubi & Ogbona were 1/2 as decent as Ibrahim 2 hav jst made their point sensibly. ‘cuz a good engineer or an experienced site worker should know dat 4 wateva values given by calculatns, a percentage z given 4 wastage. Besides d calc by Emma waz by volume and voids r nt considered.

    Personally, i aprec8 U. THANKS

  11. If only Etubi & Ogbona were 1/2 as decent as Ibrahim 2 hav jst made their point sensibly. ‘cuz a good engineer or an experienced site worker should know dat 4 wateva values given by calculatns, a percentage z given 4 wastage. Besides d calc by Emma waz by volume and voids r nt considered. AND 4 GOD’S SAKE, he allowed 4 wastages in d vol of a cement bag (0.035~0.03)

    Personally, i aprec8 U. THANKS

  12. You write-up is invaluable, but pass the right message across. Remember we are dealing with volume and strength when it comes concrete and not mathematical ratios. 1m3 of concrete will typically have cement, fine aggregate(sand), coarse aggregate (granite chipping) and water; therefore to achieve the strength of weak (1:3:6 and below) or structural (1:2:4 and above) concrete we must consider the shrinkage (water evaporating) and wastage to achieve the desired strength and dry concrete volume of 1m3. Therefore to those your calculations add a further mark-up of btw 40% to 50% on cement, sand and granite volumes; as these will retain the dry volume calculated initially off the mathematical ratio and expected design strength. Keep the good work going.

  13. pls, how many blocks will be needed to fence a plot of land 50sq ft by 100sq ft and to also build a twin 3 bedroom flat of 2toilets and bath from the foundation. hope 947sq ft ie 88sq meter is ok for a moderate 3 bedroom flat with a masterbedroom. if not please help me state the minimum size. i dont want too big structure. thanks

  14. I salute the effort of the writer and esteemed readers. However we must also educate ourselves on the above topic. There is a profession certified under the law of this land experienced and skilled in estimating bags of cement, blocks, dream home, structures of any kind. They are called quantity surveyors. Pls visit for more details. Although professionals in the built environ are taught some of this basic skills such as estimating, architectural design, building construction, structural design, law etc. Each profession as its own core. In summary for estimating quantities I strongly believe quantity surveyors are better estimators. Choose your adviser wisely

  15. gd day.i really appreciate ur advices on building construction. But pls i’d like 2 knw d quantity of bags of cement d@ will b used in german flooring a 35m*35m(35metere by 35meter) area of coverage using 200mm thickness cast. & also d number of trips of sand 2 b used& also 3/4’granite. Tanx

  16. I am about to start a small project in Nigeria- a four flat (with three bedrooms each) 21/2 bathrooms ; each master bedrooms are to have their own baths – replica of houses here in Dallas or Florida. So in a nutshell how many blocks do I need to complete such a project and where can I find a good architect to undertake this small contract. The proposed project is in Benin city

  17. I am about to start a small project in Nigeria- a four flat (with three bedrooms each) 21/2 bathrooms ; each master bedrooms are to have their own baths – replica of houses here in Dallas or Florida. So in a nutshell how many blocks do I need to complete such a project and where can I find a good architect to undertake this small contract. The proposed project is in Benin city…..
    We can discuss this privately if the need arises. Thank you for helping a novice like me. Nosa

  18. Ogbonna nd ibrahim…u both lack the simplest understanding…mind u, he has calculated 4 volume nd not void…both of u should stop involving on what u dont knw. Emma..u really did a good work….thumbs up.

  19. Ogbonna, etubi nd ibrahim…u both lack the simplest understanding…mind u, he has calculated 4 volume nd not void…both of u should stop involving on what u dont knw. Emma..u really did a good work….thumbs up.

  20. @mr. Albert/nosa u did nt say on w@ size of land u want 2 build ur 4 sets of 3 bd rm apartment wit individual in situ bathrm/toilets.also u did nt say if d land is on a water logged terrain or normal terrain but u can use abot 4000 blocks 4 each building dis does nt include blocks used 4 d foundation wall.if u v any further questions u can reach me tru Tanx

  21. I fink dis is rili a “gud job”. Gud job I mean is tryna educate oda field men. Pls if u notice anyfin contrary, u can also contribute instd of critisin. Its rili a gud work bt my broda, dnt u fink educatin d general public at large on dis isnt rili a gud idea? Bcos wen ur clients begn 2 knw ur little way of makn “smal smal change”, den wahala don yakpa o & u knw dis clients rarely pay wel in most contracts. Anyway sha, mouth wey go chop, go definitly chop. All d same o, Thumbs up bro

  22. Well done, Emmanuel. Your write ups have been extremely beneficial.I also thank the other contributors for adding value. I have gain much from this articles. I read production engineering but i gain much, once am ready within the shortest possible time i will consult you for advise or to recommend a contractor for me.

  23. Thanks so much for your write ups, they have been so helpful. Pls estimate how much bags of cement & trucks of sand I would need for a german floor for a bungalow of dimension: 16.2 sq meter by 14.5 sq meter

  24. I just wanna thank God 4 u, u’ve really solved a problem dat has been troubling me 4 years now….i love u n i wish u d best all d tym.

  25. Ur analysis is not detailed enough. Different elements of the building uses different mix ratio. Foundation footing, mortar, dpc cast, Iintel, arch etc. Finally for every calculation in building construction u need an allowance of atleast 25percent

  26. Well done emma,don’t listen to critics u are on the right track,fire down.most builders waste materials out of ignorance,or rather lack of accurate calculation,thanks bro.

  27. you have tried anyway but i want ogbonna to realise dat such mathematical approach should suggest he is a quantity surveyor, i want to make it clear dat the quantity surveyors approach to dat calculation wil giv d best result.

  28. Well well people are just fighting to get attention ..The core issue is how to get approximate calculations. If we stick to exact quantum’s then even a spoonful can result in errors. Even temperature, wind velocity, humidity etc etc can lead to deviations…The author is kind enough to spend his valuable time to explain, so let us further the conversation to a more corrective and accurate measures..TakecareZzz…..texaco @

  29. my name s mazzidu, bros am confuse hw did u manage 2 get d vol. of concrt 4.894 in ur caltn 4d mix ratio of 1:2:4 i beg enlighten me am frm ghana n want 2 learn more 4m u thax

  30. my name s mazzidu, bros am confuse hw did u manage 2 get d vol. of concrt 4.894 in ur caltn 4d mix ratio of 1:2:4 i beg enlighten me am frm ghana n want 2 learn more 4m u thax
    pls teach me more

  31. i agree with my critic friends. their background suggest more of a detailed calc. work. the industry has professional boundries that are not very visible. the aspect of waste isnt just enough but there is even a shrinkage factor. what he has is just volumes for batching which is hypothetically correct.

  32. what Mr Ogbonna has written is correct please do not miss lead the client and have qurral between engineer,client and contractor
    by engineer somashekhar india

  33. Mr. Emma is really doing a good job trying to educate pple and kudos to him, however there is a little error in his calculations which i will like to correct for the benfit of every one.
    1. As he has rightly said there are different mixes of concrete giving different strenghts and for use in different capacities.
    2. The commonest and most widely used are concrete 1:2:4 and 1:3:6
    3. Volume of 1 bag of cement= 50/1440=0.3472 m3 (1440 is density of cement)
    4. To calculate the volume of any constituent of concrete , you must take account of a value called dry co-efficient. Its value is 1.52.
    For example, let’s calculate the volme of cement, sand and gravel for 1 cubic meter of concrete mixed in 1:2:4 ratio.
    Vol of cement = 1/(1+2+4)*1.52=0.217 m3.
    To calculate in bags
    0.217*1440 =312.48kg/m3
    1 bag =50kg there fore we have 312.48/50=6.24 bags.
    To calculate volume of sand
    Vol of sand=2/(1+2+4)*1.52= 0.434 m3
    To calculate volume of gravel
    Vol of gravel= 4/(1+2+4)* 1.52= 0.868.
    All the above values are for 1 m3 of concrete.
    For 4.894 m3 of concrete,
    Vol of cement will be 4.894*6.24=30.54 bags.

    @ KCIS, quantity surveyors calculate volume of concrete in meter cubes, wall in meter square and so on based on drawings but they don’t calculate bags of cement or number of reinforcement bars. We all work together to compliment each other though.

    For any question, you can inbox me at

    1. @Ifelola, I want to say yours must be one of the very best comments I have seen in this site. people should realise I am more like the troubleshooter and I don’t know all, that’s why I really appreciate your contribution.

  34. how many blocks is required for 1storey building contained 6bed rooms with 1room parlour paint house. measured length 16.654, width 12070.

  35. Firstly, I would like to say to all the critiques. You wish you knew what emma has told you. Most of you are not builders, engineers or even architects nor quantity surveyors. The figures shown are quite correct. Should you wish to nit pick the figures and place yourself above the writter, please first make sure you have the intelligence to be in the business. The price of failure ultimately falls on the engineer. Thats it. Cut clean. The Criteria of voids was not raised as it is in fact an unknown quantity. For the writter to answer that would be just plain silly on his part. Some things you just have to have the intelligence to work out for yourself. If not capable, then get out of the business and save collapses eh!. Secondly, before trying to be all technical when the writer is trying to explain for the layman, simply all cannot be self thought genius on these subjects. Had you any brains at all, you would just do what every job around the world does. Simply add 10% to all volumes to cover loss voids and wastage. If you have more than that in loss and void, i assume you wont be working as you have one of two problems. Your broke for being overcompensative in loss, or, your broke because you cant find work for being either underqualified or doing slap happy work that does collapse. Either way, I dont think your as smart as you tried to make out. Good work emma….not everyone is a scientist and a little help goes a long way for some and am sure most appreciate it.

  36. Hlo mr emma if we student getting knowlegible persons like u i’m sure enviromental student will boost 4rm many part of the country even though am diploma holder in Quantity Surveying looking 4 job. I hav learn alot 4rm ur site then i will said thank u.

  37. Ifelola u are quite sound and well read…thumbs up to u for the explicitness in ur approac. But u obviously forgot to take acct for bulkiness of sand. Convertiing dat to an equivalent dry qty will require u multipling by 1.25! Cheers all.

  38. mr emmanuel never said he was an authority in estimating, he was only trying to give to society a knowledge he has, free of charge. the likes of ogbonna would’ve charged for such an information. mr ogbonna sounds like a builder. i can’t tell why you builders hate architects so passionately. we (arcs & bldrs) are brothers in the construction industry. lets love one another.

  39. All well said. In economics we are tought not to criticize except we have a superior idea. I am sure the critcs in this forum without a superior opinion got their thumbs burnt. Emma, thank you, as Erick said, nothing works in a timely schedule, not even machines, we are bound to meet hiccups here and there even in the most civilised enviroment. For every estimate, there most be room for ‘if things we equal’ which is certainly not the case. Therefore, a percentage increase in Emma’s estimate is a wise choice. He has done a great job, providing the basic fact which would guide any builder from being swindled.
    Thanks emma

  40. Emma thanks for your clear, simple and appropriate answer to the question under consideration. The response of your readers should be taken into consideration. All should note that Emma’s response is the first basic estimated quantities that you can get for cement volume in concrete and shows that he remembered well his second year course in material quantities. Expectedly, we should add constructively to what he has done. But are we ready to give freely as he did? Considerations for wastage, voids, dry volume, type of aggregates, compressive strength, rate of hydration, water, time and method of placement, whether to use additives or not are also essential. But are they within the scope of the question asked? That being said, the lesson is that Emma should humbly leave room for complimentary comments, not to be too authoritative, so as not to mislead. Nevertheless, your initiative is highly commended. Keep it up and be blessed.

  41. Do not be discouraged about what poeple are saying,the best way for the future generation to make new discoveries is by sharing all that is available at the present with them.To everyone ple never hide the little u know from people,and if someone shares what is not totally correct,just help this website by posting yr own knowledge about it bt pls dont ever critisize again on this website.

  42. I think some of the critics are builders who think their secrets had been exposed. These are people will tell building owners lies about material for themselves while they are building for the owners they are getting materials to start their own. For example the first person who started the criticism is an igbo man and you can imagine what the guy will when you are selling is trade secret, trust igbo man in business. I learnt something from Emma post and all calculation put forward are correct as I have put them to work. One of the these just said add 10% oh! This guy is exceptional these are sign of people who can see tomorrow. I also learnt that those who criticize can not make good decision they only wait for your mistakes. Critics please you don’t have anything to offer leave the site. You are helping no one. Collapsed buildings were built with people like you due to diversion of materials to from people like you.Due

  43. Dear all
    the mix proportioning is based on the properties of material based on its specific gravity , gradations etc however the proportioning of nonstructual concrete can be done by nominal methods like 1:3:6 as M10 and 1:2:4 as M15 i.e. M stands for ‘mix’ and this alphabet usually changes from country to country in some country its called like C10 and number is compressive strength at the age of 28days curing period of curing temp 27c+/-2c
    15N/ … I can give mix designs for interest ppl on the submission of test certificate of raw materials used. As i ve gross experience in the field of concrete technology

    Thanks and best regards

  44. I appreciate all i have learnt from this page recently as a Civil Engineer. In our country everybody wants to treat the whole aspect of Construction to make a living. Emma has done a good job that some of us would have had to pay for to get the knowledge, Ife did well in explaining it further. Ogbonna & Etubi, would have made their observations clearly, not by discouraging Emma. OBSERVATION: I am working on a pile cap, you also have to consider the volume of the reinforcement bars which will add up, thus covering for wastage’s. But it is advised to add +15% to carter for such wastage’s & improper batching…. THANK YOU ALL… LETS KEEP SHARING THE IDEA….

  45. I really appreciate each and every body contribution here and there all infact, those that attended environment courses or engineering courses{civil engineering}I believe there shld be conversion,in calculation which will result to same answer,either u calculate in cubic or bags.instead,of argument. kudos to the man that gave us clue of knowledge about these calculation.others profession shld bring out their idea with fine tune

  46. I appreciate ur effort of enlightment on various aspect of professions,and how u have been helpin student on there project ,ur writeup are good and educative even open and added knowlegde to all
    pls i personally need ur number and i want us to have discusion and how i can meet and where 2 meet u.pls and pls i need any of ur chartin network.dt is my requist. Tank God bless and commence ur effort,i will be api if my requist is granted.

  47. Due to several emails to my inbox requesting how to calculate volumes for plaster, i feel an obligation to return to this post to explain the procedures.
    Plaster can be done in thickness ranging from 10mm to 25mm or more depending on various factors but it is always adequate to make a plaster of 12.5mm for each wall face in nigeria so that after finishing you have your wall thickness to be about 250mm (for 9″ blocks = 225mm) and 200mm (for 6″ blocks = 150mm).
    You also need to determine your cement sand mix ratio. A ratio of 1:6 is adequate for most job.
    To calculate volume you must first know the area you want to plaster and the thickness.
    For our calculation let’s assume we need to plaster an area 20m2 at a thickness of 12.5mm
    Vol of plater = 20* 0.0125 = 0.25 m3 (12.5 converted to m2)
    Assuming a mix ratio of 1:6
    Vol of cement = 1/(1+6) * 1.52 * 0.25 = 0.0543
    Note that 1.52 is dry co-efficient. It accounts for change in volume when water is added to constituents.
    To calculate in bags
    = 0.0543 * 1440 = 78.192 kg
    = 78.192/50 = 1.564 bags ( 1 bag of cement is 50kg and 1440 is density of cement)
    Vol of sand = 6/(1+6) * 1.52 * 0.25 = 0.326m3
    Note: when calculating volumes for plaster always add additionals of at least 10% to account for wastege and uneven block work. Work men if not well supervised tend to waste materials during ranging and levelling of plaster.
    Some one also asked about workmanship, though am not very sure what he means but i guess he wants to know the area that work men will plaster in a day. This depends on standard of work desired and experience of the workmen. It also depends on your agreement, may be you are working on daily pay basis or contract basis. Workmen tend to be slower when working on daily pay basis than when working on contract basis. Averagely one gang (1 mason / labourer ) should plaster an area of about 22.5 m2 in good quality work in one day if he’s an experienced mason. ( Note that this does not include dressing. That is corners). Cheers.
    You can still direct questions to

  48. The effect of not completing a decking within a day is that;it will affect its bonding strenght.i.e its maximum bonding strenght will not be achieved.

  49. @Ifeoluwa,absolutely brilliant contributions.Undoubtedly,u shld b a colleague.kudos to mr Emma.Learning is a continous process.Even some of us wt appreciable experience in d built environment are still open to new ideas.Constructive critism shld b an integral package in our quest for advancement in knowledge. Wise people use a Quantity Surveyor for estimating and materials analysis in construction projects.(Luke 14:28) Biblical advice

  50. well I believed this man suppose to use this formular ifelola used for plastering because I have been using it before going through this web and it works. By substituting the volume of that concrete into this formular you get 32 number of bags of cement as against 23bags of cement. All the same well done is not easy.

  51. Arc,You are not only very intelligent but also take time to share same with everyone. Those contributions will go a long way to help the skilled and unskilled. I am an architect and I’ve gained from your publications. God bless you. You know what, you are simply writing your name in gold and leaving your footsteps in the sands of time. God bless the womb that bare thee. Cheers.

  52. The cement value of concrete 1:2:4 is 7.84 multiply this by the volume of what you want to cast, you will get the number of bags needed.

  53. through you guys,students can get where to start from since it’s a struggle for us.this is more practical than staying in class only reading for exams.great Work

  54. Dear learned n esteemed readers, pls do not be so quick to label mr. Ogbonna et al 4 pointing out dia observations n making reasonable criticism. Truth is, there are standards, n they must be followed #talking lives n properties here – u don’t just dream them up. Mr. Concerned professional, I totally agree : 2 achieve 1m3 of wet mix, add 50% of dry mix considering waste and consolidation. i.e, 1.5m3 dry= 1m3 wet. Thank U # to mr. Ifelola, u know ur quantities – 10x 4 enlightening d house on d gross quantities method of estimating. Fine n coarse agg. are often measured based on lorry loads. 1 lorry load = 3.81m3. From this u can see how many required.

  55. In fact am Ghanaian but dis site has really educate me a lot. Mr Emma continue to update us. Keep it up.

  56. Emma, good job! i discovered dis site recently while makin research on somtin, i read tru some of d articles posted, dey r simple, self explanatory and guide to d man on field. D most interested part is that it is frm coming a Nigerian on a zero naira, i mean u try! i also lov d way u handle critisms. D truth is dat u cnt satisfy every body. Dnt giv up or fel discouraged, som of d critiques may bred more excellent solutions lik dat of Ekubi n his partner, ifelola came up wit a 1derful solution, so to me constructive cristisms r welcom but it shld b backd wit proper explanation. I found d site to b were professional should share their field experiences so dat d beginners in construction industry wil benefit. I have experience in designs and construction but i stil find som many interestin tins to learn here, notin is wrong in hav diff solns for one qne. Emma is an architect n nt either a QS or Structural/ Civil Engr. dere4 u dnt expect him to go into details strt/civ tins, most of d article here is frm his field exprience, and it works. U can as well share ur experiences, in dat case readers wil hav diff options. Engineering is dynamic n nt static. Good engineers crave for mor knowledge and finds diff ways to achieve one task. which ever methods u applied in achieving a result if d tolerence factor or level is nt compromised or exceeded it is ok.

    keep it on bro, cheersy

  57. plz help me some one if lintel size 130’L x70’W x 5″T how much i need martial qty of cement, sand, gravel (Bajri) and steel

  58. please , how are we going to calculate for the reinforcement that already inside concrete done on site, and could you please tell me the formula/unit we are going to use and how do we arrived to that formula. Thanks

  59. Biti and Lucky are personnal here. I have learned from this site and need to share mine but my device is not structurally enabled. However, keep visiting.

  60. I really appreciate your explanation on “Cement and its Volumtion” May God empower you more knowledge.

  61. hi,, im not good in mathematics can u help me how many cement i will use in a second floor apartment with the dimension of 4 meters by 6 meters? and is it ok if i make the floor thickness of 6 inches? pls reply asap..

  62. Thanks for the heads up first in accommodating block number calculation and now foundation nitty-gritty. Thank u. I am a mechanical engineer and I intend to invest in building a 2 bedroom bungalow (2 units) in abuja, I hv my plan drawn out but want a total estimate on blocks,cement, reinforcements and roofing. Pls do I email u d sketch so u could help me out.

  63. Me think the righter is a bit conservative with his calculations. first 1m3 of concrete requires 1.52m3 of dry material for mixing due to shrinkage of concrete on setting.
    for 1:2:4 mix,
    Cement = 1/7*1.52*1440/50 (i.e 6.25 bags per m3 of concrete)
    Sand = 2/7*1.52 (i.e 0.43 m3 per m3 of concrete)
    Gravel = 4/7*1.52 (i.e 0.86 m3 per m3 of concrete)

    But please note that some designers use performance specification for the concrete such as stregth at 28days which necessitates the use of design mix

  64. mister how did you arive at your conclusion? did you allow for shrinkage and waste at all? from my own calculation for cement is 28.77 approximately 29bags having allow for shrinkage and waste.

  65. Searching for hiding knowledge is kandle of your life. It will also help you to discover youself. Thanks for the teachers, not lectuers.

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