Concrete Calculator

Calculate concrete volume in cubic yards, cubic feet and cubic metres for slabs, footings and columns, including bag counts and waste allowance.

Length (ft)

Width (ft)

Thickness (in)

Quantity

Waste allowance (%)

Cubic yards

1.36

Cubic metres

1.038

Cubic feet

36.7

Pre-mixed bags required

Bag counts by pre-mixed concrete bag size
Bag size	Yield	Bags needed
80 lb	0.60 ft³	62
60 lb	0.45 ft³	82
40 kg	0.018 m³	58

Formula

Volume = length × width × thickness (slab) · π × r² × height (column)

Results are converted using exact factors: 1 yd³ = 0.764554857984 m³ and 1 ft³ = 0.028316846592 m³. Bag yields are the manufacturer-published dry-mix yields for standard 4,000 psi mixes; check your product bag, as high-strength and fast-setting mixes yield slightly less.

Cite this page

UnitConvertLab. (2026). Concrete Calculator. UnitConvertLab. Retrieved from https://unitconvertlab.com/zh/tools/concrete-calculator