How to Estimate Bricks and Concrete for a Wall or Slab
Work out the number of bricks for a wall or the cement, sand and aggregate for a concrete slab, with a waste allowance.
Ordering building materials by guesswork is costly. Estimating bricks and concrete is simple arithmetic once you know the volume, and the Brick and Concrete Calculator does the steps for you.
Quick answer
For a wall, enter length, height and thickness (half-brick 115 mm or full-brick 230 mm). For concrete, enter length, width and thickness. The calculator adds a waste allowance and shows quantities.
Bricks for a wall
A standard brick with mortar occupies about 0.00194 m³ (225 × 112 × 75 mm with joints is a common size used in estimates; local bricks vary).
- Wall area = length × height (subtract large openings).
- For a half-brick wall, about 50 bricks per m²; for a full-brick wall, about 100 per m².
- Add 5 to 10 percent for breakage and cutting.
Example: a 10 m × 3 m half-brick wall is 30 m². 30 × 50 = 1,500 bricks, plus 7 percent = about 1,605 bricks.
Concrete for a slab
- Volume = length × width × thickness, in metres.
- For a slab of 4 m × 3 m × 0.1 m the volume is 1.2 m³.
- Add 5 to 10 percent for spillage and uneven ground.
- Divide by the mix ratio. For a 1 : 2 : 4 mix, parts total 7, and dry volume is about 1.54 times the wet volume.
The calculator shows cement, sand and aggregate quantities from the chosen ratio.
Tips
- Always check the real size of your local bricks; some are smaller.
- Order a little more than needed; matching bricks later is hard.
- Concrete strength depends on the mix and on curing, not only on the ratio. A structural slab needs an engineer's specification.
- Keep dry sand and cement covered from rain.
This is an estimate for planning, not a structural design.
