How many bricks do you need?
Brickwork is counted per square metre of wall face, and the number barely changes from job to job because the brick size does not. This brick calculator takes the wall size, subtracts the openings, and gives the bricks or blocks plus the sand, cement and wall ties that go with them.
Sixty bricks per square metre
A standard UK brick is 215 × 102.5 × 65mm. Add a 10mm mortar joint and each brick occupies 225 × 75mm of wall face, which is 59.3 per m² — the figure everyone rounds to 60. A double skin wall, the two leaves of a cavity, needs 120.
Ten blocks per square metre
A 440 × 215mm block with the same 10mm joints takes up 450 × 225mm, so 9.88 per m², rounded to 10. Blocks cover ground faster, which is why inner leaves and garden walls are often built in block and faced with brick.
The joints are already counted
Because the 60 and 10 figures are worked out from the brick plus its joint, you never add anything for mortar thickness. Adding it again is the most common way a brick order comes out too high.
Worked example: a 5m × 2m wall
10 m² of wall face, 5% wastage for cuts and breakages.
| Wall type | Units per m² | Units to order | Sand | Cement |
|---|---|---|---|---|
| Single skin brick | 60 | 630 bricks | 0.63 t | 7 bags |
| Double skin brick | 120 | 1,260 bricks | 1.26 t | 13 bags |
| Blockwork | 10 | 105 blocks | 0.63 t | 7 bags |
A double skin wall also needs about 25 wall ties at 2.5 per m². Cement is counted in 25kg bags, mixed roughly 1:5 with building sand.
Mortar, ties and openings
How much mortar
The trade rule of thumb is one tonne of building sand and ten 25kg bags of cement per 1,000 bricks. Thicker joints, frogged bricks laid frog-up and generous buttering all push it higher, and some always ends up on the ground.
Wall ties
Cavity walls need ties between the leaves, about 2.5 per m² at 900mm horizontal and 450mm vertical spacing, plus extra ties down both sides of every opening. Exposed or tall walls need more, so follow the drawings rather than the average.
Doors and windows
Take openings off the wall area: a 2.5 m² opening in this wall drops the order from 630 bricks to 473. Do not expect the full saving in practice, because the cuts around a reveal waste bricks that the area calculation counts as whole.
What the calculator does not cover
Foundations
Every wall needs a footing sized for the ground and the load. Work out the concrete for it with the concrete calculator, and have anything structural specified properly — a garden wall over about a metre high, and any wall carrying a building, is not a guess-and-go job.
Damp courses, lintels and copings
A DPC above ground level, lintels over openings, cavity trays, weep vents and a coping or capping on a free-standing wall are all part of a real order. They are quantified from the drawings rather than the wall area, so add them separately.
Ordering and building
Buy in one go
Bricks vary between batches, and a second delivery months later rarely matches. Order the whole wall at once, including the wastage, and keep a few spares for repairs.
Weather and pace
Mortar does not set properly below about 3°C, and freshly laid work needs covering against rain and frost. Bricklayers also limit how high they build in a day so the wall does not move under its own weight — worth knowing when planning the schedule alongside the rest of the project budget.