Wall Mortar Mix Calculator
Wall Mortar Mix Calculator
Building a wall? This calculator estimates the volume of mortar needed for brick or block walls — factoring in joint size, unit dimensions, and wall area. Perfect for bricklayers, builders, and DIY projects in the UK or USA.
Technical Guidance
- General Bricklaying: Use a 1:3 or 1:4 cement-to-sand ratio for strong, workable mortar
- Pointing Mix: Use a weaker 1:4 or 1:5 ratio to reduce cracking and improve flexibility
- Blockwork: Often uses a 1:4 ratio, especially for load-bearing walls
- Concrete (for footings or beds): Commonly 1 part cement : 2 parts sharp sand/gravel, depending on required strength
- Mortar Shrinkage: Wet volume reduces by ~20% when mixed — always add a bit extra!
Mortar Required by Wall Size (UK & USA)
| Wall Area | Unit Type | Dimensions | Mortar Volume | Cement Bags | Sand (kg) |
|---|---|---|---|---|---|
| 10 m² | UK Brick | 215 × 102.5 × 65 mm | ~0.20 m³ | ~8 | ~800 kg |
| 20 m² | UK Block | 440 × 215 × 100 mm | ~0.35 m³ | ~14 | ~1400 kg |
| 100 ft² | US Modular Brick | 7 5/8" × 2 1/4" × 3 5/8" | ~7.5 ft³ (0.21 m³) | ~8 | ~800 kg |
| 150 ft² | US CMU Block | 16" × 8" × 8" | ~11 ft³ (0.31 m³) | ~12 | ~1200 kg |
Pro Tips
- Always order 10–15% more to cover wastage and overmix
- Use plasticiser or lime for smoother laying and better workability
- Keep mortar mix consistent throughout the job for clean finish
Common Mistakes
- Not factoring in mortar joint thickness
- Mixing volume and weight (kg vs m³) without conversion
- Using different mixes mid-wall — causes visible colour bands
FAQs
- How much mortar for 1000 bricks? → Around 0.25–0.3 m³ (8–10 bags of cement)
- Can I use ready mix mortar? → Yes — check bag for area coverage in m² or ft²
- Does mix ratio change for blocks? → Yes — often 1:4 or even 1:3 for load-bearing walls
