Concrete calculator

Add rectangular sections with length, width and thickness. See base volume, allowance and order volume, plus whole bags when you enter the yield printed on the bag.

How the calculation works

Add length × width × entered depth for every section, then multiply by (1 + allowance / 100). Divide by bag volume or yield and round up whole bags.

Measurements and packaging

• Each section is a rectangle with a thickness or depth.
• Allowance defaults to 5%.
• Bag yield is the volume of mixed concrete one bag makes, from the bag label.
• Price can be per cubic metre for bulk orders or per bag.

Worked example

A 4 × 3 m section at an entered thickness of 0.1 m has 1.2 m³ volume. With 5% extra, order 1.26 m³ or 84 bags yielding 0.015 m³ each. This is a volume example, not a thickness recommendation.

Frequently asked questions

Can I calculate without creating an account?

Yes. Calculations and locally saved projects need no registration. Saving is optional; results are available before creating a project.

Are prices provided?

No. Enter your supplier’s product coverage, packaging and price. Missing prices are never invented.

Can I reuse measurements?

Save to a named project area, then open a compatible calculator from that area.

Estimates are based on your measurements and product information. Confirm package coverage and quantities with your supplier before purchasing. Not structural or building-code advice.