Concrete Calculator
Enter the dimensions of your slab, footing, or pad. The calculator returns concrete volume and an approximate count of 80 lb pre-mixed bags for small pours.
Step 2
Enter project measurements
Use decimals if needed (e.g. 3.5).
Step 3
How to use this calculator
Measure the longest inside dimensions of your forms. Enter depth as the finished thickness. Add a waste percentage if the site is uneven or spillage is likely.
What the math is doing
Volume equals length × width × height, converted to cubic yards or cubic meters. Bag counts divide that volume by a typical 80 lb bag yield (about 0.45 cubic feet).
How to measure
Use a tape on parallel inside faces of the forms. For slopes, measure average depth or break the pour into simple rectangles.
Frequently asked questions
How much extra concrete should I order?
For flatwork, 5–10% extra is common. Irregular ground or long pump lines may need more.
Is bag count exact?
No. Manufacturers publish yield per bag; use this tool as a planning estimate and round up.
When should I order ready-mix instead?
Generally over roughly 1 cubic yard on site, ready-mix is less labor than hand-mixing bags.
Does this include reinforcement?
No. Rebar and mesh are separate; use the rebar calculator for grid steel.