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How Many Bricks or Blocks Do You Need for a Wall?

By Reeliy Editorial Team · · 3 min read

Bricks and blocks are laid with mortar between them, so each unit effectively takes up a little more space than its own size. That is the key to counting: use the unit size plus the joint, work out how many fit in a square foot or square metre, then multiply by the wall area.

This article covers a single-thickness wall, with figures for common US and UK sizes, a worked example and the usual allowance for breakage. For anything that carries load, such as a retaining wall or a house wall, follow engineered drawings and local regulations.

Units per square foot or metre

Take the length and height of one unit, add the joint thickness to each, and divide into one unit of area.

units per area = 1 ÷ ((length + joint) × (height + joint))Use the same unit for every term.

US modular brick: the actual brick is about 7⅝ in long and 2¼ in high, and a 3/8 in joint brings the module to 8 in by 2⅔ in. One brick covers 8 × 2.667 = 21.3 in², and a square foot is 144 in², so 144 ÷ 21.3 = 6.75 bricks per ft².

UK standard brick: 215 mm long and 65 mm high, with 10 mm joints, becomes 225 mm by 75 mm. That is 0.225 × 0.075 = 0.016875 m², so 1 ÷ 0.016875 = 59.3 bricks per m², which is usually rounded to 60 for a single-skin wall.

Concrete blocks: the common US block is nominally 16 in by 8 in, including its joint, so 144 ÷ 128 = 1.125 blocks per ft². A UK 440 × 215 mm block with 10 mm joints occupies 450 × 225 mm, giving about 9.9 blocks per m², usually quoted as 10.

The joint matters. If the UK brick above were laid with 12 mm joints instead of 10 mm, the unit would occupy 227 × 77 mm, so the count falls to 1,000,000 ÷ 17,479 = 57.2 per m². Always use the dimensions printed on your supplier's data sheet, because brick and block sizes differ between products and countries.

A worked example

A garden wall is 12 ft long and 6 ft high, with a 3 ft by 4 ft opening for a gate.

  1. Gross area: 12 × 6 = 72 ft².
  2. Opening: 3 × 4 = 12 ft². Net area: 72 − 12 = 60 ft².
  3. Bricks: 60 × 6.75 = 405 bricks.
  4. Allowance: 10% extra is 405 × 1.10 = 445.5, so order 446 bricks.

The same wall built from the 16 × 8 in blocks would need 60 × 1.125 = 67.5, or 68 blocks, and with a 10% allowance 74 blocks. You can run your own figures through the brick calculator, and use the area of a rectangle calculator for the wall face.

Wall thickness and bond

The figures above are for a wall one unit thick, laid in a single skin. A wall two bricks thick needs roughly double the count. Cavity walls have an inner and outer layer, often in different materials, so calculate each leaf separately.

The counts above assume bricks laid lengthwise, in the plain pattern known as stretcher bond. Patterns that turn some bricks end-on, so that only their short faces show, use more bricks for the same wall face. Ask your supplier or mason if you plan anything other than a plain layout.

Corners, ends and piers add cut pieces, and bricks at openings must often be trimmed. Some of those pieces are reusable, which is one reason a modest allowance usually covers it.

Waste, packs and mortar

  • A 5% to 10% allowance is a common planning range for breakage and cuts; use more for complicated shapes.
  • Bricks are sold in packs or pallets of a fixed quantity, so ask for the quantity per pack and round up.
  • Buy all bricks at the same time. Colour and texture vary slightly between batches, and blending from several packs while laying hides the difference.
  • Mortar is bought separately. How much you need depends on joint thickness, brick type and how the mortar is mixed, so follow the supplier's coverage figures.
  • Foundations, damp-proofing, ties and lintels are separate parts of the job.

When a project has several wall faces, the square footage calculator is handy for adding them up. To compare brick options, repeat the calculation with each unit size and compare the totals.

Try the tools
  • Brick Calculator: Enter the wall's length and height, say whether it is one brick or half a brick thick, and give the size of your brick and the mortar joint. You get the brick count, wall volume and mortar estimate.
  • Area of a Rectangle Calculator: Enter the width and length, choose a unit and read the area in square units straight away. Below you will find the formula, worked examples and the mistakes to avoid.
  • Square Footage Calculator: Type in the width and length of a room, or of the two sections of an L-shaped one, and get its area in square feet or any other unit. Add a price per square unit to see what flooring, paint or tile would cost.

This article is general information, not professional advice. See our Disclaimer and Editorial Policy.

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