Masonry calculator: blocks and mortar
Wall area less the openings, the pieces per m² and a waste allowance give the number of blocks or bricks and the kilograms of mortar.
Your figures
Result
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How we calculate it
What you enter
- Area (m²)
- Openings (m²)
- Pieces per m²
- Mortar (kg/m²)
- Waste (%)
What to watch out for
Pieces per m² come from the block size including the joint. A 5% allowance covers cuts and breakages in transport.
Formula
net = Area − Openings
pieces = ⌈ net × Pieces per m² × (1 + Waste ÷ 100) ⌉
mortar total = net × Mortar kgThe site's engine is a 1:1 port of the Android app's code.
Frequently asked questions
How many blocks does 1 m² of wall take?
The pieces per m² follow from the size of the block including its joint. Enter that figure and the calculator multiplies it by the area once windows and doors are deducted.
How much waste should you allow when laying blocks?
5% covers cutting and breakage in transport. With many cut pieces, angles or narrow piers it is worth raising that figure.
The same formula in the app LiczMat for Android uses the same engine offline — with the material catalogue and results saved into a project. Download