Bags of Concrete Calculator — 40, 60 & 80 lb Bags

Find out how many bags of pre-mix concrete a small pour needs. Enter the area and thickness and the calculator shows the count in 40, 60 and 80 lb bags side by side, so you can pick whichever bag size is cheapest at your store.

How it works

Volume (cu ft) = length × width × (thickness ÷ 12), plus your waste allowance. Bags = volume ÷ bag yield, rounded up: an 80 lb bag ≈ 0.60 cu ft, a 60 lb bag ≈ 0.45 cu ft and a 40 lb bag ≈ 0.30 cu ft.

Frequently asked questions

How many 80 lb bags of concrete are in a cubic yard?

A cubic yard is 27 cubic feet and an 80 lb bag yields about 0.60 cu ft, so a cubic yard takes roughly 45 bags of 80 lb concrete.

What size bag of concrete should I buy?

80 lb bags are the best value by volume but heavy to handle; 60 lb are a common compromise; 40 lb suit small repairs. This calculator shows all three so you can compare store prices.

When is bagged cheaper than ready-mix?

For small pours — a few cubic feet up to roughly a cubic yard — bags usually beat a ready-mix short-load fee. Above about a yard, ready-mix is normally cheaper and faster.

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Estimates are for planning only. Material yields, densities and code requirements vary — confirm quantities with your supplier and local building code before ordering.