Concrete Calculator

How to use

1. 1Pick a shape for the first pour and type the dimensions. Use feet plus inches in imperial mode, or meters in metric mode.
2. 2Add more pours with Add pour if your job has multiple sections (for example a slab plus four footings).
3. 3Set a waste allowance (10% is the common default) and choose the unit you want the total shown in.
4. 4Pick a featured bag size and read the bag count for all three sizes. Optionally enter a price per bag or a ready-mix price per cubic yard or meter, plus a currency.
5. 5Read the total volume, bag counts, and estimated cost on the right, and use Copy summary to share the takeoff.

About this tool

Concrete Calculator turns the shape and dimensions of one or more concrete pours into the volume of concrete you need to buy, the number of pre-mix bags it takes, and an optional cost estimate. Pick a shape for each pour: a slab or rectangle (length x width x thickness, for patios, driveways, garage floors, and footings), a round column or sonotube (diameter x height, for deck piers and round footings), a square column (side x side x height), a round post hole (diameter x depth, for fence posts), or a set of stairs (rise, run, total width, and number of steps). Add as many pours as you need in a single calculation, give each a name, and the total is summed automatically. Switch the input system between imperial (feet plus inches) and metric (meters), and show the result in cubic yards, cubic meters, or cubic feet. The waste allowance defaults to 10%, the standard safety margin for spillage, over-pour, and uneven sub-base, and you can change it to match your job. Bag counts are computed for all three common pre-mix sizes using the manufacturer's published wet yields: 80 lb bags at 0.60 cubic feet each, 60 lb bags at 0.45 cubic feet each, and 40 lb bags at 0.30 cubic feet each. Add a price per cubic yard or per cubic meter to estimate a ready-mix delivery quote, or a price per bag to estimate the cost of buying bagged concrete at a hardware store. Useful for homeowners planning a DIY pour, contractors writing a quick estimate, and inspectors checking a takeoff. All math runs in your browser; the dimensions, prices, and bag counts you enter never leave your device.

Free to use. Works in your browser. No signup, no login.