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Concrete Calculator

Calculate concrete volume in m³ and number of 25 kg bags.

Best for: Pouring a slab, path, footing or post base.

Complete guide
Country (units):

Input

How it's calculated & sources
The Concrete Calculator uses the standard method for this calculation. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Concrete?
A concrete calculator finds the volume of concrete needed for a slab, footing or column, and estimates the number of bags.
Why does Concrete matter?
The concrete volume to order or mix. Ready-mix is sold by the cubic metre or yard; bags list their yield on the packaging.
How is Concrete calculated?
Volume is length times width times thickness, with every measurement in the same unit, giving cubic metres or cubic yards. The number of bags is the volume divided by each bag's yield, plus a small margin for spillage and uneven ground. Formula: Volume = Length x Width x Thickness.
What are common concrete mistakes?
Mixing units, for example thickness in centimetres but length in metres.
When should you use the Concrete Calculator?
Pouring a slab, path, footing or post base.

What is the Concrete Calculator?

A concrete calculator finds the volume of concrete needed for a slab, footing or column, and estimates the number of bags.

How the Concrete Calculator works

Volume is length times width times thickness, with every measurement in the same unit, giving cubic metres or cubic yards. The number of bags is the volume divided by each bag's yield, plus a small margin for spillage and uneven ground.

Volume = Length x Width x Thickness

Concrete volume and 25 kg bags by slab size

2 × 2 m10 cm0.435
3 × 3 m10 cm0.979
4 × 3 m10 cm1.2105
5 × 4 m15 cm3261

Common mistakes to avoid

  • Mixing units, for example thickness in centimetres but length in metres.
  • Leaving out a waste allowance for spillage and subgrade variation.
  • Forgetting that thickness must be in the same unit as the other dimensions.
  • Ignoring reinforcement and formwork in the plan.

Keywords: concrete, cement, volume, bags.

Sources: General construction guidance

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Concrete Calculator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Concrete Calculator?+

Concrete Calculator uses the standard concrete formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Concrete Calculator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Concrete Calculator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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# Concrete Calculator — the free tool I keep coming back to

Calculate concrete volume in m³ and number of 25 kg bags.

Try it: https://freetoolsgalaxy.com/tools/concrete-calculator
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The fastest way is to use a free in-browser concrete calculator: https://freetoolsgalaxy.com/tools/concrete-calculator. Calculate concrete volume in m³ and number of 25 kg bags.

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