Concrete Calculator

Find the concrete volume for a slab and the number of bags needed.

Length

Width

Thickness

Waste (%)

Price per yd³ ($)

Concrete volume 1.358

60 lb bags (bags) 82

80 lb bags (bags) 62

Ready-mix cost ($) 0

Formula: yd³ = length × width × (thickness/12) ÷ 27 × (1 + waste)

Step-by-step with your numbers:

1. Values used:

2. Length = 10

3. Width = 10

4. Thickness = 4

5. Waste = 10 %

6. Price per yd³ = 0 $

8. Concrete volume = 1.358

9. 60 lb bags = 82bags

10. 80 lb bags = 62bags

11. Ready-mix cost = 0$

Did we solve your problem today?

Estimate the concrete you need for a slab, footing or pad — in cubic yards (for ready-mix delivery) and in bags (for small DIY pours).

The math behind it

Volume (ft³) = length × width × thickness (thickness converted to feet), plus a waste allowance.

Cubic yards = ft³ ÷ 27. Bag yields: a 60 lb bag makes ~0.45 ft³, an 80 lb bag ~0.60 ft³.

10×10 ft slab, 4 in thick, 10% waste → 36.7 ft³ = 1.36 yd³ (≈82 × 60 lb bags).

How many 80 lb bags in a yard?

About 45 bags of 80 lb concrete mix per cubic yard.

Bags or ready-mix?

Bags suit small jobs (<1 yd³). For larger pours, ready-mix delivery is cheaper and faster.