Easily and accurately calculate concrete slab and footing pours and get estimating tips
Updated May 1, 2023
Use these free concrete calculators to quickly estimate how much concrete you need for slabs, footings or columns. It is a good idea to overestimate the amount of concrete needed so you won't come up short on the jobsite.
Enter the depth, width and length of your concrete slab to calculate the number of cubic yards, meters or concrete bags needed to complete your project.
Enter the depth, width and length of your concrete footing to calculate the amount of concrete needed to complete your project.
Enter the diameter and height of your concrete column to calculate how much concrete you need for your project.
To find the amount of concrete you need, use our concrete calculator or this simple volume formula: Length × Width × Thickness. Measure your project and multiply the dimensions to get cubic feet or meters. Divide by 27 to convert cubic feet to cubic yards. Using our concrete calculator ensures accuracy and saves time.
When ordering concrete from a ready mix supplier, one cubic yard is equal to 27 cubic feet. So, if your project measures 10 ft long, 10 ft wide, and 4 in thick, you'll need slightly more than 1 cubic yard of concrete to complete the job.
The amount of concrete you need for a 10x10 slab depends on how thick it will be. So, for a 4-inch slab you’ll need 1.24 cubic yards (56 80lb bags), but a 6-inch slab requires 1.85 yards (84 80lb bags). If your slab is a different size or thickness, use our calculator to determine the amount of concrete.
The number of 80 lb bags of concrete required for a slab depends on its size. Each 80-pound bag yields approximately 0.022 cubic yards of concrete. For a 4-inch thick, 100-square-foot slab, you'll need 56 bags. It's essential to calculate the volume based on your slab's dimensions.
A 50-pound bag of concrete yields approximately 0.375 cubic feet. This estimation is useful when calculating the amount of concrete needed for a project, but consider the specific dimensions of your slab to ensure you have the right quantity.
Larger jobs such as concrete driveways are easier to complete when ordering by the yard, rather than trying to mix bag after bag by hand. For smaller jobs, like a concrete walkway, small patio or footings, you should calculate the number of concrete bags instead.
Concrete is usually ordered in cubic yards, but if you're looking for concrete weight it varies depending on the type of mix being used. However, most ready mix suppliers estimate that a cubic yard of concrete weighs about 4,000 lbs. So if you need three yards, that would be around 12,000 lbs (3yds x 4,000lbs). Ask your supplier if you'd like to know the exact weight.