Cement Calculator
Cement Calculator works out Volume and Volume including waste allowance from Element being poured, How many identical elements and Length. The default figures on this page give cement bags (on-site mix) of 5.94; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
7 steps
- custom: 27 cu ft entered directly
- Volume = 27 cu ft = 1 cu yd = 0.7646 m3
- Bags: 27 cu ft / 0.6 cu ft per 80 lb bag = 45 -> 45 bags
- Weight: 27 cu ft x 150 lb/ft3 = 4050 lb
- On-site mix 1 : 2 : 4 (M15, ~2200 psi): dry volume = 27 x 1.54 = 41.58 cu ft, split 1:2:4 over 7 parts -> cement 5.94, sand 11.88, stone 23.76 cu ft
- Batch weights: cement 558.4 lb, sand 1188 lb, stone 2376 lb
- Water at w/c 0.5: 558.4 lb cement x 0.5 = 279.2 lb = 33.47 US gal = 126.69 L
Figures from concrete mix and bag yield tables, checked 31 August 2026. Its 9 worked examples are re-run on every release, last on 15 September 2026. What changed · how reference data is kept current
Sources and references
7 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the Cement Calculator calculates
Computes concrete volume in cubic feet, cubic yards and cubic metres for slabs, footings, walls, columns, stairs and curbs, then the bags, ready-mix loads, weight, cement/sand/aggregate split and cost that volume implies.
How to use this Cement Calculator
Enter Element being poured, How many identical elements, Length and Width. Volume updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Volume, Volume including waste allowance and Order this much ready-mix.
The method follows QUIKRETE Concrete Mix No. 1101 Technical Data Sheet (bag yields, ASTM C138 density), ASCE/SEI 7-22, Table C3.1-1a Minimum Design Dead Loads (stone concrete 150 lb/ft3 reinforced, 144 lb/ft3 plain), ASTM C150/C150M Standard Specification for Portland Cement (94 lb US bag), Portland Cement Association, Design and Control of Concrete Mixtures, 16th ed. (nominal volumetric proportioning, 94 lb = 1 ft3 sack) and ACI 318-19, Building Code Requirements for Structural Concrete (Table 19.3.2.1 maximum water/cementitious ratios).
What you can compare
Change one input at a time to see how it affects Volume, Volume including waste allowance and Order this much ready-mix. The inputs you can vary are Element being poured, How many identical elements, Length, Width, Thickness / depth and Height.
Understanding Volume, Volume including waste allowance and Order this much ready-mix
Footing, wall and column dimensions must come from a design by a qualified engineer or from a prescriptive table in the code adopted locally (e.g. IRC Table R403.1). This tool quantifies concrete for dimensions you supply; it does not size structural elements.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I calculate how much cement I will need?
Computes concrete volume in cubic feet, cubic yards and cubic metres for slabs, footings, walls, columns, stairs and curbs, then the bags, ready-mix loads, weight. Open “How this is worked out” beside the result to see each step for your own figures.
How many bags of cement do I need for a 12x12 slab?
On the figures this page opens with — length 10, width 10, thickness / depth 4 and waste / over-order allowance 0% — the cement bags (on-site mix) is 5.94. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the Cement Calculator?
You need Element being poured, How many identical elements, Length, Width, Thickness / depth, Height, Diameter (round column / Sonotube) and Number of steps. The page opens with default figures that give cement bags (on-site mix) of 5.94, so you can see the scale before entering your own.
What does this Cement Calculator show?
It shows Volume, Volume including waste allowance, Order this much ready-mix, Rounded up to the quarter yard, Bags needed, Total weight of dry bags, Weight of the finished concrete and Ready-mix truck loads, with the working and any warnings for your entries.
Can I check how the Cement Calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.