Mortar Mix Ratio Calculator
Calculate the exact quantities of cement, lime, and sand needed for your mortar mix. Perfect for bricklaying, blockwork, rendering, and pointing projects.
Mortar Volume & Mix Details
Enter your project volume and desired mix ratio to calculate material quantities
Total wet volume of mortar needed for your brickwork or rendering.
Proportion of cement in the mix.
Proportion of lime. Enter 0 for cement-only mixes.
Proportion of building or sharp sand.
Dry materials take up more volume than wet mortar. Standard is 1.3.
Material Quantities
Exact weights and volumes for your mortar mix
Enter your mortar volume and mix ratio above, then click Calculate Materials to see the exact quantities needed.
Common Mortar Mix Ratios
Understanding standard mix proportions helps ensure your mortar has the right strength, workability, and breathability for the job.
| Application | Mix Ratio (Cement:Lime:Sand) | Characteristics & Use Case |
|---|---|---|
| General Bricklaying | 1 : 1 : 6 | Good balance of strength and workability. Standard for most above-ground walling. |
| Blockwork / Strong Brick | 1 : 0 : 4 | Higher strength, no lime. Suitable for dense concrete blocks or damp conditions. |
| Repointing (Old Homes) | 1 : 2 : 9 | Soft, flexible, and breathable. Essential for historic buildings and soft bricks. |
| Rendering (Base Coat) | 1 : 0 : 4 | Strong and weather-resistant. Often applied with a waterproofing agent. |
| Rendering (Top Coat) | 1 : 1 : 6 | Slightly more lime for a smoother finish and better resistance to shrinkage cracking. |
Mortar Mix FAQ
Everything you need to know about mixing mortar, material ratios, and UK building standards.
The standard mortar mix ratio for general bricklaying is 1:1:6 (one part cement, one part lime, and six parts sand). The lime adds workability and flexibility, preventing the mortar from cracking. For stronger engineering bricks or damp conditions, a 1:0:3 (cement to sand) mix without lime is often used.
First, determine the total wet volume of mortar required. Multiply this by a dry volume factor (typically 1.3) to account for the voids in sand and shrinkage. Then, divide this dry volume by the total number of parts in your ratio. Multiply the result by the respective number of parts for cement, lime, and sand to get their individual volumes, which can then be converted to weight using their standard densities.
A 1:1:6 mix has a higher cement content, making it stronger and more suitable for structural brickwork, blockwork, and below-damp-proof-course applications. A 1:2:9 mix has less cement and more lime, making it softer, more flexible, and highly breathable. It is the preferred mix for repointing older, historic buildings to prevent damage to soft bricks or stone.
Building sand (also known as brick sand or plastering sand) is the standard choice for bricklaying and blockwork mortar because its fine grains create a smooth, workable mix. Sharp sand (concrete sand) is coarser and is typically used for floor screeds, concrete, or the base layer of rendering, as it provides greater strength but less workability.
There is no fixed ratio for water, as it depends on the moisture content of the sand and the desired consistency. Water should be added gradually until the mortar reaches a smooth, workable ‘butter-like’ consistency that holds its shape on a trowel without being too sloppy. Adding too much water weakens the final mortar and increases shrinkage cracking.