Brick Calculator
Enter a wall’s size once and get the bricks, cement and sand for it — sized to your brick, your joint thickness and your mortar mix.
Total area of all openings combined — leave at 0 for a solid wall.
the guide
How to calculate how many bricks you need
Every brick estimate comes down to the same idea: work out the area you’re covering, work out how much wall one brick and its mortar joint actually takes up, then divide one by the other. The calculator above does this instantly, but it’s worth knowing the maths — it’s the same method a builder uses to check a merchant’s quote, and it’s what lets you adjust the numbers when your wall doesn’t match the standard case.
Measure the wall, not the brickwork
Measure the length and height of the finished wall in metres or feet. If there’s a door, window, or other opening, measure its width and height too — you’ll subtract that area later so you’re not paying for bricks that were never going to be laid.
Work out the wall’s area
Multiply length by height to get the gross area, then subtract the area of any openings. What’s left is the net area — the actual surface of brick and mortar you need to fill.
Add the mortar joint to the brick’s size
A brick is never laid on its own — a bed and a perpend joint sit around it, typically 10mm each. So a standard UK brick doesn’t take up 215 × 65mm of wall face; with joints, it takes up roughly 225 × 75mm. That’s the number that matters for counting bricks, not the bare brick dimension on the pack.
Find bricks per square metre
Divide 1m² by the effective face area from the step above. For a standard UK brick with 10mm joints, that comes out at roughly 60 bricks per square metre for a single-skin wall. Multiply that by 2 for a double-skin (one brick) wall, since there are two leaves of brick to fill.
Multiply, then add wastage
Multiply your net area by the bricks-per-m² figure to get the raw number of bricks. Then add 5% for a plain wall, or up to 10% if there’s a lot of cutting — around corners, reveals, or a decorative bond — since cut bricks and breakages don’t come free.
Worked example
Take a garden wall 6m long and 1.8m high, no openings, built as a standard half brick wall. The area is 6 × 1.8 = 10.8m². At roughly 60 bricks per m², that’s 648 bricks before wastage. Add 5% and you’re ordering 681, which most merchants will round up to the nearest pack size.
Standard brick sizes
Brick sizes vary a little by country and manufacturer, but these are the figures worth working from if you don’t have the exact spec to hand.
| Brick type | Size (L × W × H) | Approx. per m² (single skin, 10mm joint) |
|---|---|---|
| UK standard (metric) | 215 × 102.5 × 65mm | ~60 |
| UK imperial | 228 × 108 × 68mm | ~53 |
| US modular | 194 × 92 × 57mm | ~75 |
| US queen | 241 × 79 × 79mm | ~55 |
If your bricks came with a spec sheet, use those exact figures instead — even a few millimetres of difference in height adds up once it’s repeated across an entire wall.
What changes the number of bricks
- Wall thickness. A half brick wall (single skin) uses one leaf of brick; a one brick wall (double skin) uses two, roughly doubling the count for the same face area.
- Joint thickness. Thinner joints pack in more bricks per square metre — a 12mm joint instead of 10mm can shift the count by a few percent on a large wall.
- Openings. Every door and window is bricks you don’t buy. On a wall with several openings, this easily accounts for 10–15% of the gross area.
- Bond pattern. Stretcher, English and Flemish bonds mostly change appearance and strength, not the brick count — they all still fill the same area with the same size brick.
- Wastage. Breakages, off-cuts at corners and returns, and the odd damaged brick from delivery all need covering — hence the 5–10% allowance.
Estimating cement and sand
Once you know the mortar volume — the space between the bricks, not the bricks themselves — split it by your mix ratio. A 1:4 mix (one part cement to four parts sand) is the standard choice for general house brickwork; a stronger 1:3 suits engineering brick or exposed, load-bearing work, and a leaner 1:5 or 1:6 suits low-stress garden walls.
Cement is bought by the 25kg bag in the UK, and sand is usually bought loose by the tonne or in bulk bags of around 800kg–1,000kg. The calculator above converts your mortar volume into both, factoring in the standard 30% bulking allowance for a dry, workable mix — but always round up to the next full bag or bulk bag, and ask your merchant about a small buffer for a first-time estimate.
common questions
Brick calculator FAQs
How many bricks are there in 1 square metre of wall?
For a standard UK brick with 10mm joints, a single-skin (half brick) wall uses roughly 60 bricks per square metre. A double-skin (one brick) wall uses around double that, roughly 120 per square metre.
How much sand and cement do I need per 1,000 bricks?
It depends on the mix and joint size, but a common planning figure for a 1:4 mix with 10mm joints is around 6–7 bags of 25kg cement and roughly 0.5–0.6 tonnes of building sand per 1,000 bricks. Use the calculator above for a figure matched to your own joint size and mix ratio.
Should I add extra bricks for wastage?
Yes — 5% is reasonable for a straightforward wall, rising to 10% where there’s a lot of cutting, curves, or a decorative bond involved.
What’s the difference between a half brick wall and a one brick wall?
A half brick wall is a single skin, laid flat on its stretcher face, around 102.5mm thick — typical for garden walls and internal partitions. A one brick wall is two skins thick, around 215mm, and is used where the wall needs to carry more load or stand freestanding without extra support.
Does the bond pattern change how many bricks I need?
Only marginally. Stretcher, English and Flemish bonds mainly affect appearance and strength rather than total brick count, since they cover the same wall area with the same size bricks and joints. This calculator assumes a standard stretcher bond, which holds for the vast majority of walls.