Brick calculator

How the brick calculator works

The calculator works out the area of your wall, multiplies it by the number of bricks in a square metre, then adds a percentage for cuts and breakages:

wall area = length × height − openings
bricks = wall area × 60 (single skin) or × 120 (double skin)
bricks to buy = bricks × (1 + wastage %), rounded up

It's based on the standard UK metric brick, which is 215mm long, 102.5mm wide and 65mm high, laid with 10mm mortar joints. With the joint, each brick takes up 225mm × 75mm of wall face, or 0.016875m², which works out at 59.3 bricks per square metre. The trade figure, used by UK builders' merchants, rounds that up to 60 bricks per m² for a single skin wall and 120 per m² for a double skin wall.

Single skin or double skin?

• Single skin (half-brick wall, 102.5mm thick): one row of bricks laid lengthways in stretcher bond. Used for low garden walls, planters, the outer leaf of a cavity wall and some outbuildings.
• Double skin (one-brick wall, 215mm thick): two rows of bricks side by side, tied together with headers (bricks laid end-on, as in English or Flemish bond) or wall ties. It's stronger and looks the same from both sides, so it's common for taller or more decorative garden walls.

For a cavity wall on a house extension, work out the outer brick leaf here as single skin, and the inner leaf separately in blocks. Anything structural or retaining soil should be designed by a builder or engineer.

How much mortar do I need for bricks?

Bricklayers use a long-standing rule of thumb that one tonne of building sand lays about 1,000 bricks with 10mm joints. For cement, tradespeople typically mix about 9 bags of 25kg cement per tonne of sand for a 1:4 mix (quotes range from 8 to 10), and about 8 bags for a softer 1:5 mix. The calculator uses these figures, so treat them as a guide and buy a bag or two of cement extra. Frogged bricks (with a dip on top) laid frog up use more mortar than solid or perforated bricks.

Worked example: a 10m garden wall

You want a single skin garden wall 10m long and 1.8m high, with 10% extra for cuts because of piers and coping:

• Wall area: 10 × 1.8 = 18m²
• Bricks: 18 × 60 = 1,080
• Add 10% wastage: 1,080 × 1.1 = 1,188 bricks
• Building sand: about 1.19 tonnes, so one bulk bag of sand plus a few 25kg bags
• Cement at 1:4: 1.188 × 9 = 10.7, rounded up to 11 bags

If your bricks cost 80p each, that's £950.40 for the bricks alone. Build the same wall as double skin and you need 2,376 bricks, 2.38 tonnes of sand and 22 bags of cement.

Tips before ordering bricks

• Buy all your bricks at once and mix bricks from several packs as you lay them. Colours vary between batches and even within a pack.
• Add 5% for a plain wall and 10% if there are lots of corners, piers, curves or cut bricks.
• Remember the footings. A wall needs a concrete foundation, and the courses below ground count as wall too. Use the concrete calculator for the footing.
• Coping stones along the top are bought separately by length.
• Don't lay bricks in frost. Mortar needs to cure, so protect fresh work from frost and heavy rain.

Need to measure an awkward gable or a wall with several openings? The square metre calculator adds up the areas. Finishing a garden at the same time? The gravel calculator covers paths and borders.

Last reviewed October 2026 using 2026/27 figures. This calculator gives an estimate for guidance only.