The wall volume minus the bricks, plus 15% mortar waste; frogs and cores are ignored.
Brick calculator: bricks, blocks and mortarについて
The brick count is the net wall area, after doors and windows, divided by the face area of one brick plus one mortar joint, (length + joint) × (height + joint). A waste allowance is added and the total rounded up. Mortar is the wall volume minus the bricks: net area × wall thickness × the joint share of each module, plus its own waste allowance.
The most widely used UK clay brick is 215 × 102.5 × 65 mm. With the Brick Development Association's nominal 10 mm joint it occupies 225 × 75 mm of wall face, so a half-brick wall takes 59.26 bricks per m². The default 5 × 2.4 m wall with 1.5 m² of openings needs 622.2 bricks, or 654 with 5% waste.
The count is for a single-leaf wall in stretcher bond. A two-leaf wall needs twice as many, and header courses or decorative bonds need extra bricks.
計算例
5 × 2.4 m wall, 1.5 m² window, UK bricks, 5% waste
照合元：Brick Development Association, Designing to Brickwork Dimensions (2023): co-ordinating face 225 × 75 mm with a 10 mm joint; 1 ÷ (0.225 × 0.075) = 59.26 → 60
US 8 in CMU, 20 × 8 ft wall, ⅜ in joints
Wall length
20 ft
Wall height
8 ft
Doors and windows (total area)
0 m²
Brick or block
Concrete block 15⅝ × 7⅝ in (US 8 in CMU)
Mortar joint
0.375 in
Waste allowance
0%
Bricks or blocks to buy
180 pcs
Per square foot
1.125 pcs/ft²
照合元：NCMA TEK 4-2A: 8/9 ft² per unit → 112.5 blocks per 100 ft²; 160 ft² × 1.125 = 180
US modular brick mortar per 100 ft², ⅜ in joints, no waste
Wall length
10 ft
Wall height
10 ft
Doors and windows (total area)
0 m²
Brick or block
Modular brick 7⅝ × 2¼ in (US)
Mortar joint
0.375 in
Waste allowance
0%
Mortar waste allowance
0%
Mortar (wet volume)
5.5 ft³
照合元：Brick Industry Association Technical Note 10, Table 4: 5.5 ft³ of mortar per 100 ft² of modular brick with ⅜ in joints
よくある質問
How many bricks are in a square metre?
59.26 for a half-brick wall of standard UK bricks, which rounds up to 60. The Brick Development Association gives the 215 × 102.5 × 65 mm brick a co-ordinating size of 225 × 112.5 × 75 mm with its nominal 10 mm joint, and 1 ÷ (0.225 × 0.075) = 59.26. A one-brick wall, two leaves thick, needs 118.5 per m².
How many bricks are in a square foot?
About 6.75 US modular bricks. Brick Industry Association Technical Note 10 lists 675 per 100 ft², using the nominal 8 × 2⅔ in module in which three courses rise 8 in. With the specified 7⅝ × 2¼ in brick and ⅜ in joints this calculator's geometry gives 6.86 per ft², 1.6% more, because three courses then measure 7⅞ in.
How many concrete blocks do I need for a wall?
Divide the net wall area by the face of one block plus its joint. NCMA TEK 4-2A says an 8 × 16 in block laid with ⅜ in joints covers 8/9 ft², which is 112.5 blocks per 100 ft², or 119 with its 5% waste allowance. The UK preset, a 440 × 215 mm block with 10 mm joints, covers 0.10125 m², so 9.88 blocks per m².
How much mortar do I need for 1,000 bricks?
Brick Industry Association Technical Note 10 gives 8.1 ft³ of mortar per 1,000 US modular bricks with ⅜ in joints and 10.3 ft³ with ½ in joints, before waste, and says to add 15–25% for mortar waste. In the UK, the Brick Development Association's mortar guide says one tonne of ready-mixed lime:sand, gauged with cement on site, lays about 1,000 bricks.
How much extra brick should I order for waste?
At least 5%, according to Brick Industry Association Technical Note 10, which says to work out the net count, including extra bricks for the bond pattern, before adding waste and to go higher where job conditions warrant. On the default 10.5 m² wall, 5% turns 622.2 bricks into 654. Mortar gets its own allowance of 15–25%.
「Brick calculator: bricks, blocks and mortar」の精度はどのくらいですか？
Brick Development Association — Designing to Brickwork Dimensions (2023): 215 × 102.5 × 65 mm work size, 225 × 112.5 × 75 mm co-ordinating size; Brick Industry Association Technical Note 10 — Dimensioning and Estimating Brick Masonry (675 modular brick per 100 ft²; waste 5% brick, 15–25% mortar); NCMA TEK 4-2A, Estimating Concrete Masonry Materials — 8/9 ft² per 8 × 16 in unit; 119 units per 100 ft² with 5% waste.