Brick & Block Calculator
Find how many bricks or blocks you need for a wall, plus the mortar, cement and sand. Advanced adds more walls, doors and windows, cavity walls, your own brick size, mix ratio and cost.
Typical: about 60 per m² with 10 mm joints.
The outer leaf uses the brick above. Typical UK practice: ties 900 mm apart across and 450 mm up, about 2.5 per m². Follow your local building rules.
10 mm (about ⅜ in) is the usual joint. Changing a size switches to "My own size".
Typical door about 0.9 × 2.1 m (3 × 7 ft), window about 1.2 × 1.2 m (4 × 4 ft).
5% extra is usual. Use 10% for many corners and openings.
1:4 for strong or below-ground work, 1:5 or 1:6 for general walls (typical).
Typical: an 80 lb (36 kg) bag of mortar mix makes about 0.67 cu ft (19 L). Check your bag.
How your bricks are worked out
Each brick plus its joint takes a little area. Divide the wall by it, add extra, then work out the mortar between them.
- 1
Bricks per m²
(215+10) × (65+10)= 0.016875 m² each1 ÷ that = 59.26
- 2
Wall area
5 × 2= 10 m²
- 3
Count the bricks
10 × 59.259 = 592.6× 1.05 = 622.2= 623 bricks
- 4
Mortar, cement, sand
0.194 m³ mortar3 × 25 kg cement14 × 25 kg sand
Read more: the formula, worked examples in metres and feet, typical sizes and tips
Each brick takes up its own face plus one mortar joint along the side and one along the top. So the number of bricks in a square metre (or square foot) is 1 divided by that bigger area. Multiply by the wall area, less doors and windows, and by the number of skins, then add a little extra for cuts and breakage. The mortar is the space in the wall that the bricks don't fill.
The formula
bricks per m² = 1 ÷ ((brick length + joint) × (brick height + joint))
wall area = length × height (+ ½ × length × gable height) − doors and windows
bricks = wall area × bricks per m² × skins × (1 + extra % ÷ 100), rounded up
mortar = wall area × skins × (depth − bricks per m² × length × height × depth) + collar joints, then + extra %
dry mix = mortar × 1.33
cement = dry mix ÷ (1 + sand parts) × 1440 kg/m³ · sand = dry mix × sand parts ÷ (1 + sand parts) × 1600 kg/m³
bags = mass ÷ bag size, rounded up
Worked example
In metres. A wall 5 m long and 2 m high is 10 m². A UK brick is 215 × 65 mm, so with 10 mm joints each brick takes 0.225 × 0.075 = 0.016875 m², which is 1 ÷ 0.016875 = 59.26 bricks per m². A half-brick wall needs 10 × 59.26 = 592.6 bricks, and with 5% extra 592.6 × 1.05 = 622.2, so buy 623 bricks.
One m² of the wall is 0.1025 m³ (it is 102.5 mm thick). The bricks fill 59.26 × 0.215 × 0.065 × 0.1025 = 0.084885 m³, so the mortar is 0.1025 − 0.084885 = 0.017615 m³ per m². For 10 m² that is 0.17615 m³, and with 10% extra 0.1938 m³ of wet mortar. The dry mix is 0.1938 × 1.33 = 0.2577 m³. In a 1:5 mix, cement is 0.2577 ÷ 6 = 0.04295 m³ × 1440 = 61.85 kg (3 bags of 25 kg) and sand is 0.2577 × 5 ÷ 6 = 0.2148 m³ × 1600 = 343.6 kg (14 bags of 25 kg).
In feet. A wall 20 ft long and 6 ft high is 120 sq ft. A US modular brick (7⅝ × 2¼ in) with ⅜ in joints takes 8 × 2⅝ = 21 sq in, so 144 ÷ 21 = 6.857 bricks per sq ft. 120 × 6.857 = 822.9 bricks, and with 5% extra 864 bricks.
Typical sizes
| Brick or block (typical) | Per area, one skin |
|---|---|
| UK brick 215 × 102.5 × 65 mm, 10 mm joint | 59.26 per m² (about 60) |
| US modular brick 7⅝ × 3⅝ × 2¼ in, ⅜ in joint | 6.86 per sq ft (tables: 6.75) |
| US standard brick 8 × 3⅝ × 2¼ in, ⅜ in joint | 6.55 per sq ft |
| Indian modular brick 190 × 90 × 90 mm, 10 mm joint | 50 per m² (500 per m³ of wall) |
| Concrete block 440 × 215 mm, 10 mm joint | 9.88 per m² (about 10) |
| CMU block 15⅝ × 7⅝ in (16 × 8 nominal), ⅜ in joint | 1.125 per sq ft (112.5 per 100 sq ft) |
Sizes are typical and vary by maker and country, so check your bricks. The mortar figures assume solid bricks with no frog or holes filled. A frogged brick laid frog up, or holes filled, needs more mortar. The 1.33 dry-mix factor and the 1440 kg/m³ cement and 1600 kg/m³ sand densities are common rules of thumb, checked 11 October 2026. Wall tie spacing and mortar strength are set by your local building rules.
Tips
- Order all the bricks at once so the colour matches, and mix bricks from several packs as you go.
- A one-brick wall also needs a bond (English or Flemish) that ties the two skins together. The brick count is the same.
- Keep sand covered so it stays dry, and only mix as much mortar as you can use in about two hours.
Common questions
How many bricks are in a square metre?
A UK brick is 215 × 65 mm on its face. With 10 mm mortar joints each brick takes up 225 × 75 mm, so 1 ÷ (0.225 × 0.075) = 59.26 bricks per m² of a half-brick wall, usually rounded to 60. A one-brick wall needs twice as many, about 119 per m².
How many bricks per square foot?
A US modular brick (7⅝ × 2¼ in) with ⅜ in joints takes up 8 × 2⅝ in, so 144 ÷ 21 = 6.86 bricks per sq ft. Tables often say 6.75 because they set the joints so three courses make exactly 8 in. A 20 × 6 ft wall needs about 823 bricks, or 864 with 5% extra.
How much cement and sand do I need for 1000 bricks?
1000 UK bricks in a half-brick wall use about 0.297 m³ of wet mortar. Dry materials are about 1.33 times that, 0.395 m³. In a 1:5 mix that is about 95 kg of cement (four 25 kg bags) and about 527 kg of sand, before any extra for spills.
How many blocks are in a square metre?
A standard 440 × 215 mm concrete block with 10 mm joints takes up 450 × 225 mm, so 1 ÷ (0.45 × 0.225) = 9.88 blocks per m², usually called 10. A US CMU block (15⅝ × 7⅝ in) with ⅜ in joints takes 16 × 8 in, so 1.125 blocks per sq ft.
What is the difference between a half-brick and a one-brick wall?
A half-brick wall is one brick thick, with bricks laid lengthways (102.5 mm for a UK brick). A one-brick wall is two skins side by side, 215 mm thick, so it needs twice the bricks plus a mortar joint between the skins. A cavity wall has two separate leaves with a gap, held with wall ties.
How much extra brick should I order?
Add about 5% for cut bricks at ends and openings and for breakage. Add more, up to 10%, for walls with many corners, openings or a fancy bond. Order all the bricks at once so the colour matches, and mix bricks from several packs as you lay them.
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