Concrete Calculator
Find out how much concrete your project needs. Enter the length, width and thickness of a slab and how many you are pouring, and the calculator shows the volume in cubic yards, cubic feet and cubic meters, along with how many 60 lb and 80 lb bags that works out to.
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.
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.
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.