How Many Bags of Concrete Do I Need?

Counting bags

The calculator is set to 60 lb bags and a 6 × 6 ft pad 4 in thick, the size of a small landing or an air-conditioner base. Change the shape and sizes to your job, and pick your bag from the list: the result counts whole bags, rounded up, and the table under it shows the same concrete in 40, 50, 60 and 80 lb bags and in 20 and 25 kg bags.

Every count starts from the yield the maker prints: the volume of mixed concrete one bag makes. For Quikrete Concrete Mix that is about 0.30 cu ft from 40 lb, 0.375 from 50 lb, 0.45 from 60 lb and 0.60 from 80 lb, so the yield is the same 0.0075 cu ft for every pound. Fast-setting post mixes are close: Quikrete Fast-Setting gives 0.375 cu ft from a 50 lb bag.

Kilogram bags

Outside the US, mixes come in kilograms. Sakrete’s data sheet gives 0.41 cu ft (about 11.6 litres) for the 25 kg bag it sells in Canada and 0.50 cu ft for 30 kg, and Easy Mix Concrete, sold in Australia, makes 10 litres from 20 kg. Switch the calculator to metres to work in cubic metres.

When the bag isn’t on the list

Choose “Another bag” and type the yield from the bag or its data sheet, in cubic feet or litres. If only the weight is printed, the makers above all make about 0.0075 cu ft per pound, or about 0.47 litres per kilogram, which is close enough to plan with; check the bag before you buy.

Bags for common volumes

Whole bags for each volume as the makers state their yields, with no waste added; the last column is one cubic yard with 10% extra.

Yields from each maker's data sheet, linked above, checked October 2026.