Mortar Calculator
Estimate cement, sand and mortar bags for your wall — from simple DIY projects to full trade builds.
- Standard UK brick face: 215 × 65 mm
- Mortar joint thickness: 10 mm
- Wastage allowance: 5%
- Mix ratio: 1:5 (cement:sand)
- Dry volume factor: 1.3× wet volume
- Cement density: 1440 kg/m³ (25 kg bags)
- Sand density: 1600 kg/m³ (~850 kg bulk bags)
- Ready-mix mortar: approx. 0.015 m³ per 25 kg bag
Use this mortar calculator to estimate how much mortar you need for brickwork or blockwork. If you haven’t yet worked out your material quantities, start with our Brick Calculator or Block Calculator to estimate your bricks or blocks first.
PRO TIP: Most people underestimate how much mortar they need due to wastage and variation on site. Adding 5–10% extra is standard practice to avoid running short mid-project.
Need to estimate bricks or blocks first?
Use our:
- Brick Calculator
- Block Calculator
How to use the mortar Calculator
- Enter your wall length and height
- Select brickwork or blockwork
- Choose your wall thickness
- Adjust the mortar mix ratio if needed
- Click calculate to see the mortar volume and materials required
How Mortar Quantities Are Calculated
This calculator estimates the volume of mortar needed based on wall area, unit size, and joint thickness. It then converts this volume into material quantities using standard mortar mix ratios.
Mortar is made from:
- Cement (or lime)
- Sand
- Water
The mix ratio determines how much of each material is required.
Common Mortar Mix Ratios (UK)
- 1:4 – Strong mix, suitable for structural work
- 1:5 – General-purpose bricklaying
- 1:6 – Weaker mix, more flexible and workable
Weaker mixes are often preferred as they reduce cracking and improve bonding.
What Affects How Much Mortar You Need?
- Joint thickness
- Brick or block size
- Wall type (single vs double skin)
- Workmanship and wastage
- Absorption rate of bricks
Actual usage on-site can vary, so it’s always recommended to allow for extra material.
How Much Mortar Do You Need Per 100 Bricks?
As a rough guide:
- Around 0.3 m³ of mortar per 1,000 bricks
- This equals roughly:
- 6–7 bags of cement
- 0.8–1 tonne of sand
These are estimates and will vary depending on joint size and wall type.
FAQs
How much mortar do I need for a wall?
The amount depends on wall size, brick or block type, and joint thickness. This calculator estimates mortar volume and converts it into materials like cement and sand.
How many bags of mortar do I need?
This depends on your mix ratio and wall size. The calculator shows cement in 25kg bags to make ordering easier.
What is the standard mortar mix ratio in the UK?
Common ratios are 1:4, 1:5, and 1:6 (cement to sand). The correct mix depends on the strength required and exposure conditions.
How much sand do I need for mortar?
The amount of sand depends on the mix ratio and total mortar volume. For general brickwork, you’ll typically need around 4–5 parts sand to 1 part cement.
How much mortar do I need per 100 bricks?
As a rough estimate, you’ll need around 0.03 m³ of mortar per 100 bricks. This can vary depending on joint thickness and workmanship.
Related Calculators
Brick Calculator – Estimate how many bricks you need for a wall, including mortar and wastage
Block Calculator – Calculate concrete blocks required based on wall dimensions and block size