Concrete Calculator
Estimate the concrete for a slab, footing or pad. Enter the area and thickness to get cubic yards for ready-mix or the number of bags of concrete mix. Nothing is uploaded — it all runs in your browser.
You'll need
Small jobs use bags of mix; larger pours are ordered by the cubic yard as ready-mix. Weight assumes ~2.4 t/m³; add a waste % for spillage.
How to use the concrete calculator
- Measure your area Length × width for a rectangle, or the diameter for a circle.
- Set the depth How thick a layer you're laying.
- Read the result Cubic yards for bulk, tons for weight-priced material, or bags for a small job — add a waste % for spillage.
Concrete Calculator FAQ
How much concrete do I need for a slab?
Multiply the slab area by its thickness for the volume in cubic feet, then convert to cubic yards (ready-mix) or divide by a bag’s yield for bag count. This calculator does both.
How many 80 lb bags of concrete in a cubic yard?
An 80 lb bag yields about 0.6 cubic feet, so roughly 45 bags make a cubic yard. This calculator counts bags at 0.6 ft³ each.
Should I add extra?
Yes — add about 5–10% for spillage, uneven subgrade and over-excavation. Use the waste % field.