Material
Skin
Wall dimensions
Openings to subtract (doors, windows; leave at 0 if none)
| Wall | Amount |
|---|
Mortar: sand and cement
| Mortar volume needed | 0 m3 |
| Cement (25kg bags) | 0 |
| Sand | 0 t |
| Sand in bulk bags (0.85t usable each) | 0 |
How this calculator works
Bricks and blocks are laid to a defined rate per square metre once a standard joint width is fixed. A UK standard brick is 215 x 102.5 x 65 mm; with a 10mm mortar joint on every face, that works out to 60 bricks per square metre of single-skin wall. A 100mm concrete block (440 x 215 mm face, 10mm joints) works out to 10 blocks per square metre. Double skin, for a cavity wall or a solid 215mm wall, simply doubles the count and the mortar. Net wall area is length × height minus any door or window openings you list, and wastage on top covers breakages and cut bricks or blocks at corners and openings.
Working out the mortar
Mortar volume uses a defined rate per square metre per skin (0.025 m3 for brickwork and roughly 0.01 m3 for blockwork are typical starting points; both are editable if your bricklayer or merchant quotes differently). From that volume, the sand and cement split follows the same logic as the concrete calculator: a mix ratio (cement to sand), a bulking allowance because loose dry materials need more volume than the finished, compacted mortar, and standard bagged cement and sand densities to convert volume into bags and tonnes. General brickwork commonly uses a 1:4 or 1:5 mix; a stronger 1:3 suits engineering brick or exposed, load-bearing work, and a weaker 1:6 suits ordinary internal blockwork.
Choosing a wastage allowance
5% covers normal breakages and offcuts on a straightforward rectangular wall. Push it toward 10% for a wall with several openings, corners, or a decorative bond pattern that generates more cut units.
What this calculator does not check
This tool gives quantities only. It doesn't check whether the foundation below is adequate for the wall's height and loading, whether a cavity wall needs wall ties at the correct spacing, damp-proof course requirements, or whether the wall is load-bearing and needs building control sign-off (a garden wall over about 1m high, or any wall supporting a structure above, should be checked against current Building Regulations). Always confirm structural requirements separately.
Related tools
Pouring the footing this wall sits on? Use the concrete calculator. Buying sand loose or in bulk bags rather than as part of the mortar mix? See the aggregate calculator.