What is the best mortar mix for bricklaying?

A 1:4 mix (one part cement to four parts building sand) is the standard general-purpose mortar for most bricklaying. Use a stronger 1:3 mix for exposed walls, below DPC, and chimney stacks. A weaker 1:5 mix is acceptable for internal walls in sheltered conditions. Adding plasticiser improves workability.

How much mortar do I need per 1000 bricks?

For stretcher bond (half-brick wall), you need approximately 0.5 m³ of mortar per 1000 bricks. This works out to around 4-5 bags of cement and 0.7-0.8 tonnes of building sand using a 1:4 mix. Always add 10-15% extra for wastage.

What type of sand is used for mortar?

Use building sand (also called soft sand or bricklaying sand) for mortar, not sharp sand. Building sand is finer and smoother, which makes the mortar workable and easier to lay. It should comply with BS EN 13139. The sand colour will affect the final mortar colour.

Can I use plasticiser instead of lime in mortar?

Yes, liquid plasticiser (such as Feb-Mix) is the modern alternative to lime in mortar. It improves workability, making the mix 'fatty' and easier to work with. Use it according to the manufacturer's instructions — typically one capful per mix. It also helps frost resistance in cold weather.

How long does mortar take to set?

Mortar takes approximately 24-48 hours for an initial set and 28 days for full cure. Do not lay bricks or blocks if the temperature is below 2 degrees Celsius or dropping, as frost can destroy fresh mortar. In hot weather, dampen bricks before laying to prevent them drawing moisture from the mortar too quickly.

Mortar Calculator — Cement & Sand Quantities for Bricklaying UK

Mortar Calculator — How Much Cement and Sand Do I Need?

Calculate the cement and sand needed for mortar. Covers bricklaying, blockwork, pointing, and rendering with standard UK mix ratios.

Input Method

Choose how to specify the quantity

Wall Area

Total wall area to be covered

Application

Different applications use different mortar rates

Mix Ratio

1:4 is standard for most domestic work

Material Prices (optional)

Cement (per 25kg bag)

Building Sand (per tonne)

How We Calculate This

This calculator determines the volume of mortar needed, then breaks it down into cement and sand quantities based on your chosen mix ratio.

Mortar rates by application

Bricklaying (half-brick): 0.03 m³ mortar per m² (~1kg per brick)
Bricklaying (full-brick): 0.06 m³ mortar per m²
Blockwork: 0.012 m³ mortar per m² (~1.5kg per block)
Pointing/repointing: 0.01 m³ mortar per m²
Rendering (15mm coat): 0.015 m³ mortar per m²

Mix ratio material quantities

Per cubic metre of mortar:

1:3 (strong): ~12 bags cement (25kg), ~1.5 tonnes building sand
1:4 (general): ~9 bags cement (25kg), ~1.5 tonnes building sand
1:5 (internal): ~7 bags cement (25kg), ~1.5 tonnes building sand

Standards

Mortar should comply with BS EN 998-2 (Specification for mortar for masonry). Mortar designation should be selected based on exposure conditions per BS 5628 / PD 6697. General-purpose mortar (M4) is suitable for most domestic applications.

Frequently Asked Questions

Last updated: February 2026

All calculations are estimates. Verify with your supplier.

Mortar Calculator — How Much Cement and Sand Do I Need?

How We Calculate This

Mortar rates by application

Mix ratio material quantities

Standards

Frequently Asked Questions

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