Free calculator
Brick and block calculator
Enter the wall size, take out the doors and windows, choose your brick or block, and get how many to buy plus the mortar volume.
Result
- Wall area to build
- 12.4 m²
- Units per area
- 59.3 per m²
- Bricks or blocks (exact)
- 735
- To buy with 5% waste
- 772
- Mortar volume (wet)
- 0.218 m³ (218 L)
Single-skin wall, one unit thick. Mortar is the geometric joint volume; add about 20 to 30% for waste and see the bag for dry-mix yield.
How it works
Each brick occupies its own size plus one mortar joint on the top and one on the end. Units per square metre = 1 ÷ ((length + joint) × (height + joint)). A UK standard brick (215 × 65 mm with a 10 mm joint) works out at about 60 per square metre; a US modular brick at about 7 per square foot; an 8 × 8 × 16 in concrete block at 1.125 per square foot.
The net area is the wall face minus openings. Mortar volume is the wall volume minus the volume taken by the units themselves, which is exactly the bed and head joints. Real jobs use more, because mortar is wasted and joints are not perfectly uniform, so add 20 to 30% and check the dry-mix bag for its yield.
The result is for a single-skin wall one unit thick. For a double-skin or cavity wall, calculate each skin separately.
Frequently asked questions
- How many bricks are in a square metre?
- About 60 standard UK/EU bricks (215 × 65 mm) laid with 10 mm joints. Thin-joint or larger-format bricks change the figure, which is why the calculator uses the actual size and joint.
- How many bricks per square foot?
- About 7 US modular bricks with 3/8 in joints, or 1.125 concrete blocks of 8 × 8 × 16 in.
- How much waste should I allow for bricks?
- Five percent is usual for straight walls. Add more for walls with many cuts, corners or damaged deliveries.
- Does it calculate mortar bags?
- It gives the mortar volume. Bag yields vary a lot between products, so take the volume, add waste, and use the yield printed on the bag you are buying.
Guides
- How many bricks per square metre (and per square foot)?
Bricks and blocks per square metre and per square foot for the common formats, how the mortar joint changes the count, and what to order for a 10 m² wall.