How much concrete do I need?
Multiply length × width × depth using compatible units, then convert the volume to the unit used by your supplier. Add an appropriate allowance for uneven excavation and waste.
Run the scenario.
The calculator is prefilled with the example above. Change any input and the result updates immediately in your browser.
- Depth must be converted to the same base unit as length and width before multiplying.
- Concrete is commonly ordered by volume rather than area.
- Real forms and ground conditions can require extra material.
- Supplier minimums and truck-load rules are separate from the geometric calculation.
Volume requires depth
A slab that looks like 100 square feet on the surface needs a volume calculation because concrete has thickness. Convert the depth to compatible units before multiplying all three dimensions.
The calculator handles the unit conversion and gives an ordering estimate.
Add a practical buffer
Forms, excavation and subgrade are rarely mathematically perfect. Many projects order slightly more than the exact geometric volume to avoid coming up short.
Quick questions.
Can I use square footage alone?
No. Concrete quantity depends on depth as well as surface area.
Does the estimate include waste?
Only if the tool provides and you enter a waste allowance, or you add one separately.
Read the answer. Inspect the standard.
This page is connected to a working calculator, visible formula and public editorial policy. “NL Verified” refers to engineering checks, not external professional review.
Use the full calculator when the answer needs more depth.
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