Concrete volume calculator

Volume and bag estimate for slabs and post holes — bag count uses the yield you enter.

Shape

Check your bag's label — ≈9–14 L for typical 20–30 kg bags.

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Up to 1,000 m³ and 50% extra allowance. Bag count uses the yield you enter — brands differ, so verify on the bag. Posts are treated as perfect cylinders.

How to use

  1. Pick slab or post-hole shape.
  2. Enter the dimensions and bag yield.
  3. Read the volume and bags to buy.

What it supports

Slab = L×W×D, post = cylinder ×count. Bag yield is an input (≈9–14 L for typical 20–30 kg bags) — check your brand. Up to 1,000 m³ and 50% extra.

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