Ordering bricks or blocks for a wall comes down to one multiplication after the rate per square metre is settled - but that rate itself comes from the brick's size plus its mortar joint, not a number picked out of thin air. This guide walks through where 60 bricks per square metre comes from for an ordinary garden or house wall, when that figure doubles or changes, and how to turn a wall's dimensions into a number you can actually take to a merchant.
How many bricks per square metre?
A half-brick wall - a single skin, one brick thick, laid in the common stretcher bond you'll see on most garden walls and internal leaves - takes 60 standard bricks per square metre. Build it up to two skins thick and the count doubles to 120 bricks per square metre; that's the figure for a full one-brick-thick wall or for a cavity wall's outer leaf where it's laid as a full brick skin rather than tied back to a block inner leaf. Both figures assume the standard UK brick size and a 10mm joint, and both are nudged up slightly from the raw arithmetic to leave a small margin for ordering.
Bricks and blocks per square metre (standard UK sizes, 10mm joints)
| Wall type | Unit size | Count per m2 |
|---|---|---|
| Half-brick (single skin) | 215 x 102.5 x 65mm brick | 60 |
| One-brick (double skin) | 215 x 102.5 x 65mm brick | 120 |
| Standard block wall | 440 x 215mm block | 10 |
Where the 60-per-m2 figure comes from
A standard UK brick measures 215mm long, 102.5mm wide and 65mm high. Laid flat in stretcher bond, the face on show is the 215mm length by the 65mm height, and a 10mm bed of mortar surrounds it on the two sides that touch its neighbours. Add that 10mm to each of the two visible edges and each brick's actual footprint on the wall becomes 225mm by 75mm - 0.225m × 0.075m = 0.016875 square metres (m2), joint included. Flip that around to find how many fit in a square metre: 1 ÷ 0.016875 = 59.26. Suppliers round that up to a clean 60 for ordering purposes, and the small margin above 59.26 is nowhere near enough to matter once normal wastage is added on top.
One-brick and cavity walls
Stack two half-brick skins back to back and the count simply doubles - no fresh sum needed, just 60 x 2 = 120 bricks per square metre for a solid one-brick-thick wall. A cavity wall built with a brick outer leaf and a block inner leaf works the same way but the two skins use different rates: price up the brick face at 60 per m2 and the block face using its own count below, then add the two totals together rather than searching for one blended figure.
How many blocks per square metre?
The other common walling unit is the standard concrete block, typically 440mm by 215mm on its visible face, used for garden walls, outbuildings and the inner leaf of a cavity wall. Apply the identical arithmetic: a 10mm joint on each of the two showing edges takes the effective footprint to 450mm by 225mm, or 0.45m × 0.225m = 0.10125m2 per block. 1 ÷ 0.10125 = 9.88, which rounds up to a neat 10 blocks per square metre - a tidier result than the brick figure simply because a block's bigger face makes the 10mm joint a smaller fraction of the total.
Allowing for wastage
Order 5 to 10 percent above the raw count to cover cuts, breakages and the occasional damaged unit that turns up in any delivered pack. Sit toward 5 percent for a simple run of wall with no corners or openings; push nearer 10 percent once the job involves returns, an opening cut into the middle of a course, or a bond that isn't a plain running pattern, since each of those generates offcuts that a straight wall never sees. It's ultimately a judgement call on how fiddly the layout is - err on the higher side, since a short-delivered order costs far more in a second trip than a handful of spare units costs sitting in the garden.
Mortar for the joints
Every brick or block laid needs mortar in the joint around it, so the volume needed tracks the unit count, not the wall area by itself. A reasonable planning figure is 0.0005m3 of mortar per standard brick, though actual consumption shifts with how deep the frog is filled and how generous each bricklayer leaves the joints. Feed a brick or block total - or a wall area instead, if that's what you've got to hand - into the mortar calculator and it works out cement and sand quantities from there, factoring in that dry sand and cement shrink down once mixed and pressed firmly into place.
Worked example: counting bricks for a garden wall
Take a garden wall 6m long and 1.8m high, built as a half-brick skin: 6 × 1.8 = 10.8m2 of wall face. At 60 bricks per square metre, that's 10.8 × 60 = 648 bricks before any allowance for waste. Adding 10 percent for the corners and a gate opening: 648 × 1.10 = 712.8, so around 713 bricks are actually needed. Rounding up to a clean order quantity gives 720, which absorbs a pack that's slightly short on delivery plus a handful of accidental breakages on site. Where a wall has more than one opening or an odd shape, the brick and block calculator deducts door and window areas automatically and adds the mortar quantities in the same step.
FAQ: bricks and blocks per square metre
Do different bonds change the brick count? Yes. A plain stretcher bond, where every brick shows only its long face, is the most material-efficient pattern and gives the 60-per-m2 figure above. Flemish bond and English bond both mix in header bricks (shown end-on) alongside stretchers for extra strength and a decorative pattern, and typically need somewhat more bricks per square metre than plain stretcher bond because of how the headers interlock through the wall. Treat the 60 figure as a stretcher-bond baseline and check with whoever's laying the wall if a different bond is planned.
Are seconds or reclaimed bricks the same size as new standard bricks? Often not. Reclaimed bricks in particular can vary noticeably from the 215 x 102.5 x 65mm standard depending on their age and original manufacturer, and seconds are sometimes sold specifically because they're slightly under or over size. Measure a sample of what you've actually been quoted before ordering by the standard count, since a few millimetres per brick adds up across a whole wall.