Brick Wall
Brick or block count and mortar estimate for a full masonry wall.
OpenMortar Calculator
Calculate cement bags and sand volume for brick or block mortar, render coats and masonry bedding, based on area, joint thickness and mix ratio.
What this calculates
Calculates the mortar volume, cement bags and sand needed for a masonry or render application based on area, layer thickness and mix ratio.
Formula used
Volume = length × height × thickness. Volume with waste = volume × (1 + waste %). Cement bags = volume × bags/m³ (by ratio). Sand = volume × 1.05 m³/m³.
Worked example
A wall of 4 m × 2.5 m with 1.5 cm joints and 1:4 mix: volume = 0.15 m³. With 10% waste: 0.165 m³. Cement: ceil(0.165 × 11) = 2 bags. Sand: 0.165 × 1.05 ≈ 0.17 m³.
Mix ratio guide
1:3 (strong): exposed masonry, below-grade or high-humidity walls. 1:4 (standard): most exterior and interior brick or block walls. 1:5 (lean): lightweight interior partitions, basecoat render, non-structural applications.
When not to use this calculator
Pre-blended mortar products (dry-bag mixes) have their own coverage rates — use the manufacturer's data instead. This calculator is for site-batched mortar.
How to use this calculator
- Enter the area of the surface to mortar (length × height for a wall, or m² directly).
- Enter the layer thickness in centimeters — 1–1.5 cm for standard brick joints, 1–2 cm for render coats.
- Select the mix ratio — 1:3 for strong/exposed applications, 1:4 for standard masonry, 1:5 for lightweight partitions.
- Enter the waste factor — 10% covers over-mixing and joint overfill losses.
- Click "Calculate mortar" to see cement bags and sand volume.
Mortar types — choosing the right mix
Not all mortar is the same. Using the wrong type causes premature failure, staining or structural issues:
- Type S (1:0.5:4.5 cement:lime:sand, USA): High-strength, below grade, retaining walls, chimneys. Equivalent to a lean 1:3 site-batched mix.
- Type N (1:1:6, USA): General-purpose above-grade masonry. Most common for interior and exterior walls. Equivalent to 1:5 site mix.
- Class M2 (Europe EN 998-2): Mortar with declared compressive strength ≥ 2.5 MPa — comparable to Type N / 1:4 mix.
- Pointing mortar: Stronger than the masonry itself is wrong — it traps moisture and stresses the brick face. Always use a weaker mix than the masonry unit for pointing.
Water content — the most critical variable
The water-cement ratio determines mortar strength more than any other factor. A mix that is too wet (flowing consistency) may halve the final strength. The correct consistency for bedding mortar is "stiff but workable" — it should hold its shape when formed into a ball but not crumble. Adding water to revive setting mortar is not acceptable; discard batches that have begun to stiffen.
Frequently asked questions
What cement-to-sand ratio should I use?
1:3 for structural/exposed masonry. 1:4 for standard walls. 1:5 for lightweight interior or render coats.
How many bags per m²?
With 1:4 mix and 1.5 cm thickness: about 0.5 bags (25 kg) per m². Thicker joints need more.
What's the difference between mortar and concrete?
Mortar has no coarse aggregate (gravel). It bonds bricks and blocks. Concrete adds gravel for structural strength.
How thick should mortar joints be?
Brick: 10–15 mm. Concrete block: 10–20 mm. Render coat: 10–15 mm per coat.
Assumptions
- 1:3 mix: 14 bags (25 kg) per m³. 1:4: 11 bags. 1:5: 9 bags.
- Sand: 1.05 m³ per m³ of mortar in all cases.
- Does not include water, admixtures or tools.
- Waste applied to net mortar volume.
Technical warning
Actual cement consumption varies with cement type, sand grading and water content. Always conduct trial mixes for structural applications.
Common mistakes
- Adding too much water — this reduces mortar strength.
- Using dirty or clay-rich sand.
- Not dampening dry bricks before laying — they absorb water from the mortar.
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