Concrete Calculator

Enter the dimensions for concrete and use the Concrete Calculator to compare a few options. Confirm important quantities with product instructions or a qualified tradesperson.

ft
ft
in
Concrete needed
1.23 yd³
Cubic feet33.33 ft³
Cubic meters0.94 m³
60 lb bags75
80 lb bags56

Buy about 5–10% extra to allow for spillage and uneven ground.

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How it works

Volume is length times width times thickness, with thickness converted from inches to feet, giving cubic feet. Dividing by 27 gives cubic yards. Bag counts assume a 60 lb bag yields about 0.45 cubic feet and an 80 lb bag about 0.6 cubic feet of set concrete.

How to use the Concrete Calculator

Enter the values requested by the tool and start with one realistic example. Read the result together with its unit or label, then change one input at a time if you want to compare options. Keeping a note of the original figures makes the calculation easier to check later.

Allow for waste, product packaging, site conditions and local requirements. A tradesperson or supplier can confirm the quantity needed for the actual job.

Frequently Asked Questions

How much extra concrete should I order?
Adding roughly 5 to 10 percent is wise to cover spillage, uneven subgrade and waste, so you do not run short mid-pour.
How many bags are in a cubic yard?
About 60 bags of 60 lb mix or 45 bags of 80 lb mix make a cubic yard, so larger pours are usually cheaper with ready-mix delivery.
Does this work for footings and columns?
This version is set up for rectangular slabs. For footings or columns, calculate each section as a rectangular volume and add them up.