Brick Calculator

Brick quantity example with a gate opening

For a 10 m long, 1 m high wall with a 1 m wide opening through its full height, gross area is 10 square metres and the opening is 1 square metre. Net brickwork is therefore 9 square metres. Using the UK standard setting of 60 bricks per square metre, one skin and 10% waste gives 9 × 60 × 1.10 = 594 bricks. At 400 bricks per pack, that is 2 packs containing 800 bricks.

The 206 bricks above the calculated order quantity come from rounding to full packs. If the supplier sells split packs, enter the actual offered pack size or use 1 to see the individual-brick quantity. For several openings, add their areas first. This quantity example does not specify a safe wall design, foundations or reinforcement.

Using the brick calculator for US modular bricks

Choose US modular in the brick-format field as well as imperial units. Switching metres to feet alone does not change the brick format. The selected format determines bricks per unit of wall area; the unit switch only changes how lengths and areas are entered and displayed.

A 100 square foot net wall face is about 9.2903 square metres. At the calculator estimate of 75 US modular bricks per square metre, one skin and 10% waste, the order quantity is 767 bricks after rounding up. A supplier using the rounded rule of 7 bricks per square foot may estimate 770 instead. Use the supplier coverage figure as a custom format when available. Use the mortar calculator to estimate the cement and sand for the joints.

How many bricks do I need?

Start with the face area of the wall: length × height, or the area you already know. Take off the doors, windows and gates at their full size, then multiply by the number of bricks in a square metre for your brick format. A UK standard brick laid with 10 mm joints gives 60 to the square metre in a half-brick (single skin) wall, and 120 if the wall is a full brick thick. US modular bricks are smaller on the face, so about 75 per square metre, or 7 per square foot.

Then add waste. Every corner, opening and pier means cut bricks, some arrive broken, and a few get dropped. 5% is enough for a plain straight run; 10% is the realistic figure for a wall with openings or returns. The result is rounded up to whole bricks and then to whole packs, because a merchant sells facing bricks by the pack and the odd loose brick is not always available.

The formula

Bricks per square metre by format

The figure comes from the brick face plus one joint each way: (215 + 10) × (65 + 10) mm = 0.016875 m², and 1 ÷ 0.016875 = 59.3. If your bricks or joints are a different size, do the same sum and enter the result as a custom format.

Worked example

A garden wall 6 m (20 ft) long and 1.2 m (4 ft) high, half a brick thick in UK standard bricks, no openings. Area = 6 × 1.2 = 7.2 m². Bricks before waste = 7.2 × 60 = 432. Add 10% = 475.2, rounded up to 476 bricks. In packs of 400 that is 1.19 packs, so 2 packs: 800 bricks with 324 spare. Mortar = 7.2 × 20 L = 144 L, or 0.144 m³ before waste.

Built one brick thick instead, the same wall needs 7.2 × 60 × 2 = 864 bricks before waste and 951 with 10%, so 3 packs of 400, and about 0.29 m³ of mortar. If 324 spare bricks is too many, ask about a split pack and enter that pack size above.

How to measure a wall for bricks

1. Measure the length along the base of the wall, including any returns. For a wall that turns a corner, add the two lengths together.
2. Measure the height from the damp-proof course, or from the top of the foundation, to the top of the final course. Do not include the coping or capping.
3. Deduct each opening at its full structural size, not the frame size. A standard door opening is roughly 0.9 × 2.1 m, about 1.9 m².
4. Add the area of any attached piers as extra wall: a 215 × 215 mm pier on a half-brick wall takes about one extra brick per course, roughly 13 bricks for every metre of height.
5. Decide on the thickness. A cavity wall has two half-brick leaves, of which usually only the outer one is brick; a freestanding garden wall over about 1.2 m should be one brick thick or have piers.

What else the job needs

• Mortar: about 20 L per m² of half-brick wall. The mortar calculator turns that into cement and sand for your mix ratio, with its own waste allowance.
• A concrete footing: a garden wall normally sits on a strip at least 300 mm wide and 150 mm deep. Size it with the concrete calculator.
• Damp-proof course two courses above ground, plus a coping or capping course on a freestanding wall to keep water out of the top.
• Wall ties at 2.5 per m² (900 × 450 mm spacing) on a cavity wall, and lintels over every opening.
• Blocks for the inner leaf of a cavity wall. A standard 440 × 215 mm block with a 10 mm joint runs at 10 per m², so divide the inner-leaf area by 0.1 and add 5% for cuts.

Mistakes that leave you short

• Using 60 per m² for a one-brick wall. Both skins are brick, so it is 120 per m², plus a little more mortar for the collar joint.
• Forgetting that a cavity wall shows brick on the outside only. Count the outer leaf here and the inner leaf in blocks.
• Mixing packs from different batches without blending. Facing bricks vary in colour from batch to batch; buy the whole wall in one order.
• Ordering the exact count. Bricks arrive chipped, corners need cuts, and a short pack delays the job by a delivery. Keep the spare bricks for repairs.

Planning your order

Check the inputs before buying: measure the surfaces you need, then apply an allowance and round to whole packs. The guides include worked examples you can follow alongside this calculator.