# Brick calculator: bricks, blocks and mortar

> Brick calculator: bricks or blocks for a wall from its size, openings, unit size and joint, with count per m² or ft², mortar volume and waste.

Interactive version: https://www.calcopenly.com/construction/brick-calculator
Subject: Construction and home calculators

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.

## Inputs

- **Wall length**
- **Wall height**
- **Doors and windows (total area)**
- **Brick or block** (options: Standard brick 215 × 65 mm (UK), Modular brick 190 × 90 mm (India), Modular brick 7⅝ × 2¼ in (US), Concrete block 15⅝ × 7⅝ in (US 8 in CMU), Concrete block 440 × 215 mm (UK), Custom size)
- **Brick length**
- **Brick height**
- **Brick depth (wall thickness)**
- **Mortar joint**: 10 mm is standard in metric countries; ⅜ in (9.5 mm) in the US.
- **Waste allowance**: Brick Industry Association Technical Note 10 adds at least 5% to the net brick count for breakage and waste.
- **Mortar waste allowance**: Brick Industry Association Technical Note 10 adds 15–25% to the net mortar quantity.

## Results

- Bricks or blocks to buy (pcs) — main result
- Per square metre (pcs/m²)
- Per square foot (pcs/ft²)
- Wall area after openings (m²)
- Mortar (wet volume) (m³)
- Mortar (wet volume) (ft³)

## Formula

$$
N = \left\lceil \frac{A_{\text{net}}}{(\ell + j)(h + j)} (1 + \text{waste}) \right\rceil,\quad V_{\text{mortar}} = A_{\text{net}}\, d \left(1 - \frac{\ell h}{(\ell + j)(h + j)}\right)
$$

## Worked examples

### 5 × 2.4 m wall, 1.5 m² window, UK bricks, 5% waste

- Wall length: 5 m
- Wall height: 2.4 m
- Doors and windows (total area): 1.5 m²
- Brick or block: Standard brick 215 × 65 mm (UK)
- Mortar joint: 10 mm
- Waste allowance: 5%
- **Wall area after openings: 10.5 m²**
- **Per square metre: 59.26 pcs/m²**
- **Bricks or blocks to buy: 654 pcs**
- **Mortar (wet volume): 0.213 m³**
- Checked against: Python decimal: 1 ÷ (0.225 × 0.075) = 59.26/m²; 10.5 × 59.26 × 1.05 = 653.3 → 654; mortar 10.5 × 0.1025 × (1 − 13975/16875) × 1.15 (15% mortar waste, BIA Technical Note 10)

### One square metre, UK bricks, no waste

- Wall length: 1 m
- Wall height: 1 m
- Doors and windows (total area): 0 m²
- Brick or block: Standard brick 215 × 65 mm (UK)
- Mortar joint: 10 mm
- Waste allowance: 0%
- **Bricks or blocks to buy: 60 pcs**
- 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

### Edge: Indian modular bricks divide the wall exactly

- Wall length: 4 m
- Wall height: 3 m
- Doors and windows (total area): 0 m²
- Brick or block: Modular brick 190 × 90 mm (India)
- Mortar joint: 10 mm
- Waste allowance: 0%
- Mortar waste allowance: 0%
- **Per square metre: 50 pcs/m²**
- **Bricks or blocks to buy: 600 pcs**
- **Mortar (wet volume): 0.157 m³**
- Checked against: Hand calculation: (0.19 + 0.01)(0.09 + 0.01) = 0.02 m² per brick → 50/m² × 12 m² = 600 exactly; mortar 12 × 0.09 × (1 − 0.0171/0.02)

## 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%.

### How accurate is the brick calculator?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 5 worked examples whose answers come from independent sources; for example, “5 × 2.4 m wall, 1.5 m² window, UK bricks, 5% waste” is checked against Python decimal: 1 ÷ (0.225 × 0.075) = 59.26/m²; 10.5 × 59.26 × 1.05 = 653.3 → 654; mortar 10.5 × 0.1025 × (1 − 13975/16875) × 1.15 (15% mortar waste, BIA Technical Note 10).

### Where does the method come from?

Brick Development Association — Designing to Brickwork Dimensions (2023): 215 × 102.5 × 65 mm work size, 225 × 112.5 × 75 mm co-ordinating size; Brick Industry Association Technical Note 10 — Dimensioning and Estimating Brick Masonry (675 modular brick per 100 ft²; waste 5% brick, 15–25% mortar); NCMA TEK 4-2A, Estimating Concrete Masonry Materials — 8/9 ft² per 8 × 16 in unit; 119 units per 100 ft² with 5% waste.

## Sources

- [Brick Development Association — Designing to Brickwork Dimensions (2023): 215 × 102.5 × 65 mm work size, 225 × 112.5 × 75 mm co-ordinating size](https://www.brick.org.uk/guides)
- [Brick Industry Association Technical Note 10 — Dimensioning and Estimating Brick Masonry (675 modular brick per 100 ft²; waste 5% brick, 15–25% mortar)](https://www.gobrick.com/media/file/10-dimensioning-and-estimating-brick-masonry.pdf)
- [NCMA TEK 4-2A, Estimating Concrete Masonry Materials — 8/9 ft² per 8 × 16 in unit; 119 units per 100 ft² with 5% waste](https://www.cmha.org/resource/tek-04-02a/)