Updated
March 27, 2026
Reviewed against the current calculator logic, structured content, and internal linking used on BuildCostLab.
Concrete volume tool
Concrete Calculator
Estimate concrete volume and rough material cost for slabs, footings, and post holes.
Methodology
Planning-first estimate
Use this calculator to build a rough material estimate, then confirm it against product coverage data, site conditions, and supplier pack sizes before you order.
Trust
How we publish
See the calculator methodology and editorial policy for the standards behind these pages.
Assumptions
Assumes simple shapes, typical ordering practice, and a clear volume estimate before ordering ready-mix or bagged concrete.
Common mistakes
The most common mistakes are mixing up depth units, forgetting overbreak, and ignoring uneven excavation.
Best use cases
Useful for shed bases, footing trenches, fence posts, and quick checks before ordering mixes.
How to get a better estimate
Measure carefully, apply realistic waste, and sense-check the result against how the product is actually sold.
Before you buy
Round to whole buying units and compare product coverage before buying solely on sticker price.
UK and US note
Unit wording and supplier pack conventions differ between markets, but the estimating logic still starts with geometry, waste, and whole-unit ordering.
Final buying check
Before placing an order, compare product coverage, pack size, delivery cost, and whether buying one extra unit is safer than risking a shortfall.
Explore this topic cluster
Open the full Concrete Estimating hub to move from quick estimate to deeper guidance.
How much concrete do I need for a slab?
Multiply slab length by width by depth, then add a sensible contingency amount.
Should I round up a concrete order?
Yes. Most jobs need a small margin because running short is disruptive.