The wall volume minus the bricks, plus 15% mortar waste; frogs and cores are ignored.
About the brick calculator
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.
How many bricks do I need?
Divide the wall's net area by the face of one brick plus one mortar joint, add waste, and round up. For a single-leaf wall, UK bricks (215 × 65 mm) with 10 mm joints take 59.26 per m²; US modular bricks (7⅝ × 2¼ in) with ⅜ in joints take 6.86 per ft², or 686 per 100 ft².
How to count bricks for a wall
Multiply the wall's length by its height: 5 × 2.4 m = 12 m².
Subtract the total area of doors and windows: 12 − 1.5 = 10.5 m².
Add one joint to the brick's length and height: 225 × 75 mm, or 0.016875 m² per brick, which is 59.26 bricks per m².
Multiply: 10.5 × 59.26 = 622.2 bricks.
Add the waste allowance, then round up: 622.2 × 1.05 = 653.3, so 654 bricks.
Keep the full rate until the last step. Rounding it to 60 per m² first gives 630 bricks before waste instead of 622.2, 1.25% too many.
These rates come from the unit's actual size plus the joint, before waste:
UK brick, 215 × 65 mm, 10 mm joint: 59.26 per m² (5.51 per ft²).
Indian modular brick, 190 × 90 mm, 10 mm joint: 50 per m².
US modular brick, 7⅝ × 2¼ in, ⅜ in joint: 6.86 per ft² (73.81 per m²).
US 8 in concrete block, 15⅝ × 7⅝ in, ⅜ in joint: 1.125 per ft², or 112.5 per 100 ft².
UK concrete block, 440 × 215 mm, 10 mm joint: 9.88 per m².
Technical Note 10 lists 675 modular bricks per 100 ft², slightly fewer than 686, because it uses the nominal module in which three courses rise 8 in. With 2¼ in bricks and ⅜ in joints, three courses measure 7⅞ in.
The block rate matches NCMA TEK 4-2A, which gives 8/9 ft² per 8 × 16 in block.
A wall two leaves thick, or one brick thick in UK terms, needs twice the single-leaf count: 118.5 UK bricks per m².
How much mortar a brick wall needs
Mortar fills the part of each brick-plus-joint module that the brick does not: net area × wall thickness × (1 − brick face ÷ module face). For UK bricks that share is 17.2%, so the 10.5 m² wall, 102.5 mm thick, holds 0.185 m³ of mortar.
Technical Note 10 adds 15–25% for mortar waste; at 15% the wall needs 0.213 m³ of wet mortar. For 100 ft² of US modular brick with ⅜ in joints, the same geometry gives 5.53 ft³ before waste, against 5.5 ft³ in that note's table.
Both figures are wet, mixed mortar. Convert them to bags with the yield printed on the bag or given by your supplier, since it depends on the product and the mix.
Hollow concrete blocks laid on face shells use noticeably less mortar than the full-bed estimate, and filling their cores is a separate grout quantity.
Bricks and mortar for five walls
"Default" is the 5 × 2.4 m UK wall worked above, with 5% brick waste and 15% mortar waste. The other four rows have no openings and no waste.
Those four are one square meter of UK brick, a 4 × 3 m Indian modular wall, a 10 × 10 ft US modular wall and a 20 × 8 ft wall of 8 in block, both US walls with ⅜ in joints.
Scenario
Whole units
Mortar, m³
Default
654.000000
0.212699
One square metre
60.000000
0.017615
India twelve square metres
600.000000
0.156600
US modular hundred feet
686.000000
0.156570
CMU twenty by eight
180.000000
0.199258
The Indian brick divides the wall exactly, 50 per m², so 12 m² takes 600 with nothing to round.
Mistakes that skew a brick count
Using the co-ordinating size as the brick size. The Brick Development Association's 225 × 75 mm co-ordinating size already includes the 10 mm joint. Adding the joint again gives 50.06 bricks per m², 15.5% too few.
Forgetting the second leaf. A cavity wall, or a solid wall two leaves thick, needs each leaf counted at its own unit size.
Subtracting openings twice. Deduct each door and window once, from the gross wall area.
Ordering loose bricks from a pack seller. If the supplier sells only full packs or pallets, round the whole-brick count up to their pack size after adding waste.
Inputs worth a second look
The openings figure is the combined area of every door and window in the wall.
A custom size is the brick's actual (work) size; its depth is the wall thickness used for mortar.
Brick waste and mortar waste are separate percentages.
Checked against: 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
Checked against: 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
Checked against: Brick Industry Association Technical Note 10, Table 4: 5.5 ft³ of mortar per 100 ft² of modular brick with ⅜ in joints
Questions
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%.
This calculator includes 5 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.
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