Concrete Calculator
How much concrete for your slab or footing? Enter the dimensions and we'll give you the volume in cubic feet, cubic yards, and the number of 80 lb bags.
You need about
— cubic yards
- Cubic feet: —
- 80 lb bags: —
How the concrete calculator works
volume = length × width × (thickness ÷ 12) gives cubic feet. Divide by 27 for
cubic yards. One 80 lb bag of concrete mix yields about 0.60 cubic feet, so we
divide the total volume by 0.60 and round up.
Add 10% waste for slabs poured on uneven ground, and 15% if you're a first-timer — it's cheaper to have a little left than to stop mid-pour. For exact bag counts by size, use the Concrete Bags Calculator.
Assumptions and sources
Bag yields use standard manufacturer data for 80 lb concrete mix. Results are estimates; verify local mix specifications before ordering.
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Last updated: 2026-09-09