Concrete Calculator
Concrete volume for a slab, plus an estimated bag count.
Your result appears here
Fill in the fields on the left and press Calculate. The answer, the breakdown and a copy button all land in this card.
How it is calculated
Volume = length × width × thickness; Bags = volume ÷ yield per bag, rounded up
Bag yield varies by brand and mix — the figure printed on the bag is always more accurate than a generic default.
Worked example
A 3 × 3 m slab at 10 cm thick needs 0.9 m³ of concrete — about 68 bags at 0.0133 m³ each.
Questions people ask
Yes — sub-base unevenness and spillage typically add 5–10%. Round the bag count up rather than buying the bare minimum.
For anything above roughly 1 m³, ready-mix delivery is usually cheaper and less labour than mixing dozens of bags by hand.