Concrete Calculator

Estimate slab volume, ready-mix quantity, bags, and cost.

Measurement guide

Measure slab length and width at several points and use the specified compacted thickness.

Record each area separately, keep units consistent, and update the estimate with a final site measurement before ordering.

Assumptions and limitations

This is a volume estimate, not structural design. Subgrade variation, forms, reinforcement, pump waste, and supplier minimums are separate.

Prices, tax, and delivery are user-entered planning figures, not supplier quotations.

Worked example

A 10 × 12 ft slab at 4 in thick is about 1.48 yd³ before waste; 10% allowance brings the order near 1.63 yd³.

Frequently asked questions

What waste allowance should I use?

Simple rectangles often start at 5–10%; complex patterns, many cuts, or fragile material justify more based on the installation plan.

Why is the purchase quantity rounded up?

Packages and whole pieces usually cannot be bought fractionally, so purchasing rounds up while the exact quantity remains visible.

Can I order directly from this result?

Not without verification. Re-measure, check the product label, batch and stock, and confirm with the supplier or a qualified professional.

What does the cost estimate include?

Material cost uses the rounded purchase quantity, then adds entered labor, delivery, and tax; unlisted accessories are excluded.