About this calculator
All the bricks, cement and building sand for the four walls of a room, in single or double brick, with doors and windows taken off.
How it’s calculated
Wall area = 2 × (length + width) × height − openings, measuring along the centre of the walls so the corners aren’t counted twice. Standard bricks (222 × 106 × 73 mm with 10 mm joints) need about 52 per m² for a single-brick wall and 104 per m² for double brick, plus 5% for breakage.
Mortar comes from the Concrete Society of Southern Africa’s 2024 figures per 1,000 bricks: Class II, the normal mix for load-bearing walls, is 150 kg of common cement (3 bags) and 0.6 m³ of building sand, batched 2 bags to 6 wheelbarrows; Class I is 200 kg and 0.55 m³, 2 bags to 4 barrows.
Worked example
With these inputs:
- Room length (centre of walls)
- 4 m
- Room width (centre of walls)
- 3.5 m
- Wall height
- 2.6 m
- Door and window openings
- 3 m²
- Wall
- Single brick (110 mm), 52 per m²
- Mortar
- Class II (normal load-bearing walls)
- Waste allowance
- 5%
the result is:
- Bricks
- 1,966 bricks
- Wall area (net)
- 36 m²
- Bricks per m²
- 52
- Mortar mix
- 2 bags : 6 barrows of building sand
Tips from the trade
- Order bricks from one batch so the colour matches, especially face bricks.
- Wet clay bricks in hot weather so they don’t draw the water out of the mortar too fast.
- Build in brickforce every few courses as your plans specify.
Common questions
How many bricks for a 4 × 3.5 m room?
With 2.6 m walls and 3 m² of openings, about 1,966 bricks for single brick (36 m² × 52 + 5%), or twice that for double brick.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and SANS 10400 (the National Building Regulations) and your local municipality before ordering.