Brick calculator: how many bricks do I need?

How to calculate how many bricks you need

Divide the wall area by the face area of one brick plus its mortar joint, multiply by the number of half-bricks in the wall's thickness, then add at least 5% for breakage and cuts.

Bricks per m² (one leaf) = 1 ÷ ((brick length + joint) × (brick height + joint))
Bricks                   = net wall area × bricks per m² × leaves × (1 + wastage)
Net wall area            = length × height − doors and windows

This is the face-area method behind published brick counts: a UK brick of 215 × 65 mm with 10 mm joints gives 1 ÷ (0.225 × 0.075) = 59.3 bricks per m², the familiar "60 per square metre". The Brick Industry Association lists 6.75 US modular bricks per sq ft; that figure uses the nominal coursing of three courses to 8 in, while the calculator uses the actual brick size, so it gives slightly more (6.86).

Worked example: a half-brick wall 5 m long and 2.4 m high

A 5 × 2.4 m wall of UK bricks is 12 m² × 59.3 = 711 bricks; with 5% wastage, order 747. Its 1:6 mortar needs 3 bags of 25 kg cement and 0.28 m³ of sand.

1. Area: 5 × 2.4 = 12 m².
2. Bricks per m²: 1 ÷ ((0.215 + 0.01) × (0.065 + 0.01)) = 59.3.
3. Bricks: 12 × 59.3 = 711, plus 5% = 747 to order.
4. Mortar: wall 1.23 m³ − bricks 1.019 m³ = 0.211 m³ wet.
5. Dry mortar: 0.211 × 1.15 wastage × 1.33 = 0.323 m³; cement 66.5 kg = 3 bags of 25 kg; sand 0.277 m³.

Bricks per square metre and per square foot

A half-brick wall needs about 59 UK bricks or 49 Pakistani bricks per m²; a one-brick (9 in) wall needs twice as many. The table covers each preset in the calculator.

Joints: ⅜ in for US modular and 10 mm for every other preset. A thicker joint means fewer bricks and more mortar.

9-inch vs 4½-inch walls

A 4½ in wall is one brick width (one leaf); a 9 in wall is two widths laid together, so it takes twice the bricks. For 100 sq ft of wall with Pakistani 9 × 4½ × 3 in bricks: 452 bricks for 4½ in and 903 for 9 in, before wastage.

The Pakistan and India presets start at one brick (9 in); the others start at half a brick. For the brick skin of a cavity wall or a brick veneer, choose Half brick and count each brick leaf as its own wall. Whether a wall may carry load at a given thickness is for your engineer and local bye-laws.

How much mortar for brickwork?

Mortar is what's left of the wall's volume after the bricks: wall volume − bricks × brick volume. Then add 15–25% for mortar waste, the Brick Industry Association's general rule; the calculator starts at 15%.

Turn the wet mortar into cement and sand with the mix ratio and a dry-volume factor of 1.33, a site convention rather than a standard value. For US modular bricks with ⅜ in joints this method gives 8.06 ft³ of mortar per 1,000 bricks, in line with BIA's 8.1 ft³. For other mixes or bag sizes, the cement, sand and aggregate calculator takes the mortar volume directly.

Why contractors' brick counts differ

Rule-of-thumb counts can run above the geometric count, to allow for bricks smaller than the nominal size, breakage and cutting.

For 9 × 4½ × 3 in bricks with 10 mm joints, the geometry gives about 1,154 bricks per 100 cft of brickwork. One Pakistani rate-analysis sheet we found allows 1,350, about 17% more, presumably to allow for undersized bricks and breakage. If your bricks are undersized, choose Custom and enter their measured size, rather than padding the wastage.

Brick sizes in the presets come from each country's standard or common practice: IS 1077 for India (190 × 90 × 90 mm modular, 230 × 110 × 70 mm traditional), AJK specifications for Pakistan's 9 × 4½ × 3 in brick, BIA for US modular, and Littlehampton Bricks for the 230 × 110 × 76 mm Australian standard brick, which with 10 mm joints it puts at 48.5 per m²; the face-area method gives 1 ÷ (0.24 × 0.086) = 48.4.

Assumptions and limits

The calculator counts bricks and mortar for plain walls in stretcher or English bond. It doesn't design walls or allow for special shapes.

• Piers, arches, sills and decorative bonds need extra bricks; add them as separate walls or raise the wastage.
• Openings are deducted as areas. Measure lintel bearings as wall.
• Mortar excludes frog filling. Bricks laid frog-up use more.
• Costs appear only for prices you enter.

Next, plaster the wall with the plaster calculator.

Sources

Constants and limits come from these standards, manufacturers' data and trade bodies. Where practice varies, the calculator lets you change the value.

• Technical Note 10: Dimensioning and estimating brick masonryBrick Industry Association · 2009
• IS 1077:1992 Common burnt clay building bricks: specificationBureau of Indian Standards · 1992
• Specifications, Chapter 11: Brick worksPlanning and Development Department, AJK · 2014
• How many bricks are there per square metre? (standard Australian brick)Littlehampton Bricks and Pavers · 14 August 2020
• IS 875 (Part 1):1987 Unit weights of building materials (Table 1)Bureau of Indian Standards · 1987

Found a value that doesn’t match your local practice? Tell us and we’ll review it.