Calculate sand, cement and lime quantities for common mortar mixes

Job sections

Section
Build type
Area (m²)
Coats

Materials needed

0.00 m³
Wet mortar volume
0.00 m³
Dry material volume
0.00 m³
Sand (≈ 0.0 t)

Cement bags (25kg)

Lime bags (25kg)

Mortar volume rates and mix ratios are generic approximations for standard construction practice, not an exact match to any one product or specification - actual requirements vary by brick/block size, joint width, workmanship and wastage on site. Always check against the manufacturer's guidance or your specification before ordering materials.

Mix designs

MixRatio (cement:lime:sand)Typical use

Build types

Build typeApprox. mortar volume

Mortar mix calculator

This mortar mix calculator works out how much cement, lime and sand you need for brickwork, blockwork, render or repointing. Pick a mix such as 1:1:6, set a wastage allowance, then enter the area of each part of the job in square metres.

It shows the wet and dry mortar volumes, the number of 25 kg cement and lime bags, and the sand in cubic metres and tonnes. It's free, works in your browser with no sign-up, and there's a free Windows app too.

Worked example: 20 m² brick garden wall in 1:1:6 mortar

A 20 m² single-skin brick garden wall above DPC, laid in a 1:1:6 cement:lime:sand mix (class (iii)) with 10 mm joints and the default 10% wastage.

  1. Wet mortar: 20 m² × 0.032 m³/m² = 0.64 m³.
  2. Dry materials: 0.64 × 1.3 (dry bulking) × 1.10 (wastage) = 0.92 m³.
  3. Split by parts: 1 + 1 + 6 = 8 parts, so one part is 0.92 ÷ 8 ≈ 0.114 m³.
  4. Cement: 0.114 ÷ 0.0175 m³ per 25 kg bag = 6.5, rounded up to 7 bags. Lime: 0.114 ÷ 0.05 m³ per 25 kg bag = 2.3, rounded up to 3 bags.
  5. Sand: 6 × 0.114 = 0.69 m³, about 1.1 tonnes at 1.6 t/m³.

So order 7 bags of cement, 3 bags of lime and a 1.1 tonne load of building sand.

Questions

What is the mix ratio for brick mortar?

For general brickwork above DPC in the UK the usual mix is 1:1:6 cement:lime:sand, or 1:5 to 1:6 cement:sand with a plasticiser in place of the lime. Below DPC and in exposed positions such as parapets and chimneys a stronger mix is used, typically 1:½:4½ cement:lime:sand or about 1:4 cement:sand with plasticiser.

What is the class 2 mortar mix ratio?

Designation (ii) mortar is 1:½:4 to 4½ cement:lime:sand by volume, or roughly 1:3 to 1:4 cement:sand with plasticiser. It is broadly equivalent to M6 and suits exposed brickwork and blockwork, parapets and chimneys. The calculator's Class (ii) option uses 1:0.5:4.5.

What is class 1 mortar?

Designation (i) is the strongest of the traditional mortar classes, at 1:0 to ¼:3 cement:lime:sand, and is broadly equivalent to M12. It is used where high strength and durability matter, such as engineering brickwork, retaining walls and work below DPC. The calculator's Class (i) option uses 1:0.25:3.

How do mortar classes (i) to (iv) compare with M4, M6 and M12?

BS EN 998-2 grades masonry mortar by compressive strength, and the old designations line up roughly as (i) = M12, (ii) = M6, (iii) = M4 and (iv) = M2. The stronger the mortar, the less able it is to take up small movements, so use the weakest class the specification allows.

Can I use plasticiser instead of lime in mortar?

Yes. A 1:5 or 1:6 cement:sand mix with a liquid plasticiser is common on UK sites for general brickwork and is used in place of 1:1:6 cement:lime:sand. Masonry cement, which has the plasticiser already blended in, is usually mixed at about 1:4 with sand.

How many bags of cement and how much sand do I need for mortar?

The calculator multiplies your wall area by a typical mortar volume per square metre (0.032 m³ for single-skin brick with 10 mm joints), adds 30% for dry bulking plus your wastage, then splits the total by the mix ratio. Cement is counted in 25 kg bags of 0.0175 m³ and sand is converted to tonnes at 1.6 t/m³, so treat the result as an estimate and check it against your specification before ordering.

Mortar Mix Calculator for Windows · More free construction calculators