Mortar Calculator UK
Calculate how much mortar you need for brickwork or blockwork. Get cement bag count, sand in tonnes and bulk bags, or pre-mixed mortar bags. Adjustable mix ratio.
Enter your wall details
Total face area of the wall(s) to be built - length x height
Covers cuts, breakages and uneven ground. 10% is a typical starting point.
Mortar estimate
Enter wall area to see your mortar estimate
How to calculate mortar for brickwork
The mortar volume depends on the wall type and joint configuration. For a standard half-brick wall with 10mm bed joints and perpendicular (cross) joints, approximately 15 litres of mortar are needed per m2 of wall face.
The mix ratio then determines how much cement and sand you need. A 1:4 mix means 1 part cement to 4 parts sand by volume. To allow for bulking of dry materials when mixed wet, a 25% bulking factor is applied - so you need more dry material than the final wet volume suggests.
Add 15% wastage - mortar is messy and some always ends up on the ground, on tools and in the boards. Getting the right amount on site is much better than running out mid-project.
Mortar mix guide
| Mix ratio | Typical use | Note |
|---|---|---|
| 1:3 | Strong structural, below DPC, engineering brick | Avoid with soft bricks - may cause damage |
| 1:4 | Standard brickwork, most domestic applications | Most common specification for above-DPC brickwork |
| 1:5 | General brickwork, internal block walls | Slightly weaker but still adequate for most work |
| 1:6 | Repointing, lean mixes, lime-modified mortars | Flexible - suitable for older, softer brickwork |
Worked example - 10m2 single-leaf brickwork
A 5m long, 2m high single-leaf brick wall:
- Wall area = 5 x 2 = 10 m2
- Mortar volume (net) = 10 x 0.015 = 0.15 m3
- + 15% wastage = 0.173 m3
- 1:4 mix, bulking factor 1.25: cement = 0.173 x 0.2 x 1.25 = 0.043 m3 = ~62 kg = 3 x 25kg bags
- Sand = 0.173 x 0.8 x 1.25 = 0.173 m3 = ~0.28 tonnes of sharp sand
Or approximately 15 x 25kg bags of pre-mixed mortar.
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Frequently asked questions
Planning estimates only
These results are estimates for planning purposes only. Actual material quantities can vary based on site conditions, compaction, wastage, product size, installation method and supplier guidance. For structural, safety-critical or regulated work, always consult a qualified professional.