Calculators
Concrete Volume Calculator
Calculate concrete volume for slabs, footings and round columns in cubic yards, cubic metres and premix bags, with waste.
- Runs in your browser
- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Ordering ready-mix for a slab or patio
- Counting bags for fence posts
- Estimating footing concrete
- Pricing concrete work
About this tool
What the Concrete Volume Calculator does
Concrete is ordered by volume: cubic yards in the US, cubic metres elsewhere. Multiply length by width by depth for slabs and footings, or use πr² × height for round columns, then add a waste allowance for spillage and uneven ground. Small jobs are often mixed from 60 or 80 lb bags.
Formula
- Slab volume = length × width × thickness
- Column volume = π × (diameter ÷ 2)² × height
- 1 cubic yard = 27 cubic feet; 1 cubic metre = 35.31 cubic feet
- Total = volume × pours × (1 + waste)
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Units | Feet and inches |
| Shape | Slab, footing or wall |
| Length (or column height) | 20 |
| Width | 10 |
| Thickness or depth | 4 |
| Column diameter | 12 |
| Number of pours | 1 |
| Waste allowance | 10% |
| Result | Value |
|---|---|
| Cubic yards | 2.72 |
| Cubic metres | 2.08 |
| 80 lb bags (0.6 cu ft each) | 123 |
| 60 lb bags (0.45 cu ft each) | 163 |
| Cubic feet | 73.3 |
How to read the result
Ready-mix suppliers usually sell in quarter or half-yard increments and may charge a short-load fee for small orders. Round up rather than run short mid-pour.
Above roughly a cubic yard, ready-mix is usually cheaper and gives a more consistent pour than mixing bags by hand.
Quantities are estimates. Check product data sheets and local codes, and confirm with your supplier before ordering.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
Multiply length and width in feet by thickness in feet (inches ÷ 12), then divide by 27.
About 45 bags of 80 lb concrete or 60 bags of 60 lb, based on typical yields of 0.6 and 0.45 cubic feet.
Commonly 5% to 10% for spillage, form bulging and uneven subgrade.
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