Brick and Block Calculator for a Wall
Enter the wall size, any doors or windows, the brick or block size and the mortar joint. See how many units to order with your wastage allowance, and the volume of mortar.
- Bricks or blocks to order (with wastage)
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- Bricks or blocks without wastage
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- Bricks or blocks per m² of wall
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- Net wall area
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- Mortar (wet volume)
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Assumptions
- Each brick plus one joint covers (length + joint) × (height + joint) of wall face.
- A one-brick wall counts as two leaves of the face area and is as thick as the brick length.
- Mortar = wall volume − brick volume, for solid bricks without frogs or holes; it is the wet volume.
- Openings are taken off at their full area; lintels, sills and cut bricks at corners are not counted separately.
Estimate Checked 28 October 2026 Brick Development Association: Aesthetic Brickwork General Guide (2023): UK bricks are 215 × 102.5 × 65 mm with a nominal 10 mm joint All sources
How it is calculated
- Net wall area = length × height − openings
- Bricks per m² (half brick) = 1 ÷ ((brick length + joint) × (brick height + joint)); a one-brick wall needs twice as many
- Bricks = net wall area × bricks per m²; to order = bricks × (1 + wastage %), rounded up
- Mortar = net area × wall thickness − bricks × brick length × width × height
Worked example
A 5 m × 3 m half-brick wall with 2 m² of door, UK bricks, 10 mm joints and 5% wastage.
| You enter | |
|---|---|
| Wall length | 5 |
| Wall height | 3 |
| Doors and windows (total area) | 2 |
| Wall unit | Metres (m, m²) |
| Brick or block size | UK brick 215 × 102.5 × 65 mm |
| Brick length | 215 mm |
| Brick width | 102.5 mm |
| Brick height | 65 mm |
| Mortar joint | 10 mm |
| Wall thickness | Half brick (one leaf, as thick as the brick width) |
| Wastage allowance | 5 % |
| You get | |
| Bricks or blocks to order (with wastage) | 809 |
| Bricks or blocks without wastage | 770.4 |
| Bricks or blocks per m² of wall | 59.26 |
| Net wall area | 13 m² |
| Mortar (wet volume) | 0.229 m³ |
A net wall area of 13 m² takes about 770 bricks or blocks (59.26 per m²). With your wastage allowance, order 809. The joints and bed take about 0.229 m³ of wet mortar.
Questions
Why does the joint change the count so much?
Every brick takes up its own size plus one joint on the wall face. A 10 mm joint on a 65 mm high brick adds about 15% to the height each brick covers, so fewer bricks are needed per square metre.
My brick size is not in the list
Choose Custom and type the length, width and height of your brick or block in millimetres. We only list sizes whose source we have read.
Sources and checks
- Brick Development Association: Aesthetic Brickwork General Guide (2023): UK bricks are 215 × 102.5 × 65 mm with a nominal 10 mm joint
- IS 1077:1992 Common burnt clay building bricks: clause 6.1 (modular 190 × 90 × 90 mm, non-modular 230 × 110 × 70 mm)
- US Army FM 5-428 Concrete and Masonry (1998): para 9-4 brick sizes, para 9-25 mortar joints, para 8-2 concrete block size
- NIST SP 811 (2008), Appendix B: inch, foot and square foot conversion factors
Last checked: 28 October 2026. This tool passes 6 automatic tests before every release. How we check our tools
Your numbers never leave your device: the calculation runs in your browser and nothing you type is sent or stored.
This is an estimate for ordering. Bond pattern, frogs or holes in the bricks, cutting and site practice change the real count and the mortar. Results are estimates for planning and learning. They are not a design check and do not replace a qualified engineer or your local building/electrical code.