Mortar Calculator
Mortar binds bricks, blocks, and stone. It is usually cement and sand. Getting quantities right matters for strength and cost. This tool estimates total mortar volume from wall size and a joints-only percentage of wall volume, applies a dry volume step for batching, then splits cement and sand by your mix ratio.
Cement-only help: cement calculator. Cement + sand + aggregate concrete: cement sand aggregate calculator. Plaster-style splits: plaster calculator.
Mortar quantity
Wall volume = length × height × thickness. Mortar is only a fraction of that volume (joints).
Typical guides: brickwork 20–25%, blockwork 10–15%, stonework up to 30%. Adjust for joint thickness and bond.
Default bulk densities: cement 1440 kg/m³, sand 1600 kg/m³ (override below if needed).
Volumes
Wall volume 0.00 m³
Mortar volume (in joints) 0.00 m³
Dry batching volume 0.00 m³
Materials
Cement (bulk) 0.00 m³ → 0.00 t · Bags: 0
Sand (bulk) 0.00 m³ → 0.00 t
Add roughly 5–10% extra for site wastage when ordering.
How this calculator works
Steps used here:
- Wall volume = length × height × thickness
- Mortar volume ≈ wall volume × (mortar % ÷ 100). Mortar does not fill the whole wall—only joints and beds.
- Dry batching volume = mortar volume × 1.33 when enabled (accounts for how dry materials batch versus wet placed mortar)
- Cement : sand split by ratio: each material bulk volume = dry batching volume × (its part ÷ sum of parts)
- Mass from bulk densities (defaults: cement 1440 kg/m³, sand 1600 kg/m³), plus cement bags from your bag size
Common mortar mix ratios
Different jobs use different proportions (by dry volume before water):
- 1 : 3 — high-strength masonry
- 1 : 4 — standard brickwork
- 1 : 5 — general use
- 1 : 6 — low strength or plaster backing
Stronger mixes use more cement for the same dry batching volume.
Where this calculator is used
- Brick walls
- Block walls
- Stone masonry
- Repair and patching
- General bonding and setting out orders
Use it as a planning estimate before you lock purchase quantities.
Example calculation
Wall:
- Length 5 m, height 3 m, thickness 0.2 m
Step 1 — Wall volume = 5 × 3 × 0.2 = 3 m³
Step 2 — Mortar at 25% of wall volume = 0.75 m³
Step 3 — Dry volume = 0.75 × 1.33 ≈ 1.0 m³
For a 1 : 4 mix (total parts 5):
- Cement ≈ 1 × (1/5) = 0.2 m³ — about 288 kg at 1440 kg/m³ — roughly 6 × 50 kg bags
- Sand ≈ 1 × (4/5) = 0.8 m³
Enter those dimensions and 25% in the tool to match.
Why mortar percentage matters
Mortar is not the same as wall volume—it sits in joints between units. Typical planning bands:
- Brickwork → about 20–25%
- Blockwork → about 10–15%
- Stonework → can approach 30% or more depending on coursing
The wrong percentage over- or under-orders material. Thicker joints increase mortar need—raise the percentage if your joints are heavier than standard.
Common mistakes to avoid
- Assuming mortar equals wall volume — that massively overstates mortar.
- Skipping dry volume conversion — dry sand and cement batch differently than wet placed mortar.
- Wrong ratio for loading or exposure — weak mixes can fail where stronger mortar is required.
- Ignoring joint thickness — fat joints need more mortar; reflect that in the % of wall volume.
Practical tips
- Add 5–10% extra for wastage and handling.
- Keep joint thickness consistent for predictable consumption.
- Mix in small batches so mortar does not stiffen before use.
- Adjust water for workability without flooding the mix.
Frequently asked questions
How much mortar do I need per 1000 bricks?
Many guides cite about 0.3 m³ per 1000 bricks as a rough order-of-magnitude, but joint thickness, brick size, and bond change that. This calculator uses wall volume × mortar % so you can align with your actual course height and thickness.
Can I use the same ratio for all masonry work?
No. Structural or high-exposure work often needs stronger mixes; backing or non-structural work may allow leaner ratios. Follow your specification.
What is the ideal joint thickness?
About 10 mm is typical for standard brickwork when units and workmanship are normal. Measure your site and bump the mortar % if joints run thicker.
Does mortar shrink after drying?
Yes—there can be slight shrinkage as mortar cures. The 1.33 dry-volume step helps translate wet mortar volume into dry material quantities for ordering.