How the Brick Block Calculator Works

Enter your wall length and height, choose bricks or blocks and calculator divides wall area by coordinating face size of a single unit. The coordinating size is brick or block plus its share of mortar joint, which is what actually fills the wall.

The two figures every UK estimate is built on, a standard 215 x 102.5 x 65mm brick with a 10mm joint has a coordinating face of 225 x 75mm, giving 60 bricks per square metre in a single skin wall. A standard 440 x 215mm concrete block with a 10mm joint gives 10 blocks per square metre. Both figures apply to aircrete and dense blocks alike since they share the same face dimensions.

Single Skin, Double Skin and Cavity Walls

Wall construction changes quantities more than anything else. A single skin wall in stretcher bond is one brick wide at 102.5mm and needs 60 bricks per square metre. A one brick thick wall doubles that to 120 per square metre. Traditional bonds like English or Flemish that mix headers and stretchers push a solid wall to around 82 bricks per square metre of face.

A cavity wall is really two walls, an outer leaf of facing bricks at 60 per square metre and an inner leaf of blocks at 10 per square metre, tied together across the gap with wall ties. Calculate each leaf separately and add them and remember the inner leaf needs insulation and ties on top of the masonry.

How Much Mortar You Need

Mortar is part most DIY estimates forget. Allow roughly 0.03 cubic metres of mortar per square metre of single skin brickwork. For a general purpose 1:5 or 1:6 cement to sand mix, laying 1,000 standard bricks takes around 120kg of cement and 0.4 cubic metres of building sand. Blockwork uses about 3 bags of mortar per 100 blocks laid.

Mix in batches you can use within a couple of hours and keep the mix ratio consistent across the job because a change in ratio can shift the mortar colour visibly between sections of wall.

Wastage and Ordering Tips

Add 5 percent for a straightforward stretcher bond wall and 10 percent where job involves lots of cuts, corners, piers or decorative bonds. Deduct door and window openings from your wall area before calculating, since they save real quantities on anything bigger than a small window.

Facing bricks arrive in pallets of roughly 400 to 500, so round your order to whole packs and keep spares from one batch for future repairs. Like tiles, bricks vary subtly in shade between batches and bricklayers routinely blend from three packs at once to spread any variation invisibly through wall.

Worked Example: 4m x 1.8m Garden Wall

Worth noting for garden walls, anything over 1 metre high should include piers roughly every 3 metres for wind stability and each pier adds bricks beyond the flat wall count.