Concrete Calculator
Concrete volume for slabs, footings, columns and post holes — in yards or bags.
What is Concrete?
Concrete is ordered in cubic yards (ready-mix) or bags (bagged mix). The four standard DIY pours each have their own volume shape: a slab is length × width × thickness, a footing the same long and narrow, a square column is side × side × height, and a round post hole is π × radius² × depth. Mixing the shapes up is how estimates double or halve themselves.
How it works
The chosen shape's formula runs in feet (inch inputs are converted), giving cubic feet, which divide by 27 into yards. The bag count divides the same volume by the yield of the selected bag — a 60 lb bag yields about 0.45 ft³, an 80 lb bag about 0.6 ft³ — and rounds up. Ready-mix orders round up to the half yard with 5–10% extra; an under-order pour is a cold joint in the middle of the work.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.