Concrete Calculator
Free concrete calculator to estimate cubic yards for slabs, pads, sidewalks, and footings.
Results
2Cubic yards to order
- 1.36Exact cubic yards
- 33.33Cubic feet
How it works
Volume (cu ft) = length × width × (depth ÷ 12). Divide by 27 for cubic yards, multiply by (1 + waste%), then round up for ordering.
Worked example
Example: 10 ft × 10 ft slab at 4 in thick with 10% waste → ≈1.36 cu yd after waste, so order 2 cubic yards (or 1.5 if your plant allows).
Typical slab thickness
Patios and sidewalks are often 4 inches thick. Driveways may be 4–6 inches. Garage slabs and structural work can be thicker—follow local code or an engineer’s plan.
Order a little extra
Ready-mix plants usually sell by the quarter or half yard. A 5–10% waste allowance covers uneven subgrades and short loads.
Footings and odd shapes
For trenches, use length × width × depth of the footing. For circles, use π × radius² × depth. Convert all dimensions to feet before dividing by 27.
Frequently asked questions
How much concrete for a 10×10 slab?
At 4 inches thick, a 10×10 slab needs about 1.23 cubic yards before waste. With 10% waste, plan on ~1.36 yd³ and round up to your plant’s delivery increment.
How many bags equal a cubic yard?
An 80 lb bag of concrete mix yields roughly 0.6 cu ft. You need about 45 bags per cubic yard—bulk ready-mix is usually smarter for anything over a few bags.
Should I include rebar or gravel base?
This calculator estimates concrete volume only. Base rock and reinforcement are separate materials sized from your plan.
Estimates only. Verify coverage rates and local requirements before purchasing materials. Not a substitute for professional advice.