Offcut WorksBrick and block calculator
Enter the size of the wall and what it is built from. You get the number of bricks or blocks, with joints and waste allowed for, plus the sand and cement for the mortar.
How the numbers are worked out
Bricks per m² = 1,000,000 ÷ ((brick length + joint) × (brick height + joint)). A standard brick is 215 × 102.5 × 65 mm, so with 10 mm joints that is 1,000,000 ÷ (225 × 75) = 59.3, which is why 60 per m² is the usual rule of thumb.
Blocks per m² use the same sum with a 440 × 215 mm face: 1,000,000 ÷ (450 × 225) = 9.9.
The area is the wall area less openings. Spare is added on top. A one-brick-thick wall has two leaves, so it needs twice as many bricks per square metre.
Mortar = the volume of the wall leaf minus the volume of the units, then 33% more for the dry materials, then your allowance. It is split by the mix ratio. Cement is taken as 1,440 kg per cubic metre.
Cross-check against a merchant
Travis Perkins says 1,000 standard bricks cover about 16 m² with 5% waste, and that you need about 120 kg of cement and 0.4 m³ of sand for 1,000 bricks at 1:5. For a half-brick wall this calculator gives about 114 kg of cement and 0.4 m³ of sand per 1,000 bricks with the default allowance, so it sits close to that.
What is not counted
- Wall ties, cavity insulation and cavity trays.
- Lintels, damp proof courses and air bricks.
- Special shapes, such as soldier courses, corners and returns, which need extra cutting.
- Piers and foundations. Foundations and walls above a certain height need building regulations advice.
Brick sizes
The standard UK metric brick is 215 × 102.5 × 65 mm. Imperial, handmade and reclaimed bricks differ, so check the size in the product data. If your brick is not standard, the count will differ, and the calculator does not take a custom size.
Ordering
Bricks vary slightly in colour between batches, so order all you need at once, and a few extra. Mortar is often bought as ready-mixed tubs or bulk bags, as well as cement and sand, and the bag size is the supplier's call.
Questions
How many bricks are there in a square metre?
About 59 standard bricks in a half-brick wall with 10 mm joints, usually rounded up to 60. A one-brick-thick wall has two leaves, so about 120.
How many blocks are there in a square metre?
About 10 for a standard 440 × 215 mm block with 10 mm joints.
How much sand and cement do I need for 1,000 bricks?
Travis Perkins gives about 120 kg of cement and 0.4 m³ of sand for 1:5 mortar. This calculator gives a very similar answer.
How much waste should I allow?
5% is common for bricks. More if there are many cuts, corners and openings.
Where the defaults come from
Show the 2 sources
- Designing Buildings, brick sizes. The standard metric brick size, and the co-ordinating size with joints.
- Travis Perkins brick calculator guide. About 120 kg of cement plus 0.4 m³ of sand per 1,000 bricks at 1:5, and 1,000 bricks covering about 16 m² with 5% wastage.
- The 440 × 215 mm block face is the common size but not the only one. Block thicknesses vary, so enter yours.
- The 33% dry-volume factor and the 1,440 kg per cubic metre for cement are our own working values.
- The 20% mortar allowance was chosen so the result matches the Travis Perkins figures, and the 5% spare is the same as theirs. Neither is a standard.
- We did not find a primary source for the number of bricks per square metre beyond the arithmetic from the co-ordinating size.