How to Estimate Brickwork
Quantities, Mortar and Costs Explained

Brickwork estimation trips up a surprising number of builders - not because it is complicated, but because there are several variables that all affect the final quantity. Get any one of them wrong and your order can be off by 10% or more. This guide covers the full calculation from wall area through to mortar bags and total cost.

The Standard Brick Format

In the UK, the standard coordinating brick size is 215 x 102.5 x 65mm with a 10mm mortar joint. This gives a coordinating size of 225 x 75mm per brick face - which means:

• Half-brick wall (102.5mm thick): approximately 60 bricks per m2
• One-brick wall (215mm thick): approximately 120 bricks per m2

These figures are for standard stretcher bond. Other bonds (English bond, Flemish bond) change the number of headers and therefore the quantity per m2.

Step 1 - Calculate Wall Area

Measure the length and height of each section of wall and multiply them together. Add all sections.

Then deduct openings: each door opening and window opening should be measured and subtracted from the gross wall area. Do not forget to include reveals (the sides of the opening) if they are also to be bricked - these are sometimes omitted by mistake.

Step 2 - Apply Brick Count Per m2

Multiply your net wall area by the appropriate brick density:

• Half-brick wall: net area x 60
• One-brick wall: net area x 120

This gives you a theoretical brick count before waste.

Step 3 - Add Waste Allowance

No brickwork job goes to plan without some breakages and off-cuts. Standard waste allowances:

• Simple straight runs with few openings: 5%
• Normal residential work with windows and doors: 10%
• Curved walls, complex details or hand-made bricks: 15%

Multiply your brick count by 1.05, 1.10 or 1.15 accordingly. Always round up to the nearest full pack or delivery quantity.

Step 4 - Calculate Mortar

Mortar volume is often estimated as approximately 0.5m3 of mortar per 1,000 bricks for a half-brick wall in stretcher bond. In practice this varies with joint thickness and finish (flush, bucket handle, recessed).

Mortar is typically mixed at a ratio of 1 part cement : 4-6 parts soft sand by volume, depending on application:

• General brickwork: 1:5 or 1:6
• Below DPC or retaining walls: 1:3 or 1:4 (stronger mix)
• Pointing: 1:4 or 1:5

A standard 25kg bag of cement makes roughly 0.02m3 of mortar when mixed at 1:5.

Step 5 - Sand Quantities

Soft sand (also called building sand or bricklaying sand) is sold in 25kg bags or loose by the tonne. As a rough guide:

• 1 tonne of soft sand = approximately 750 litres of loose volume
• At a 1:5 mix, you need roughly 5 bags of sand per bag of cement

Worked Example

A half-brick garden wall, 12m long x 1.2m high, with one opening of 1.0 x 1.0m:

• Gross area: 12 x 1.2 = 14.4m2
• Less opening: 1.0 x 1.0 = 1.0m2
• Net area: 13.4m2
• Bricks: 13.4 x 60 = 804 bricks
• Add 10% waste: 804 x 1.10 = 885 bricks (order 900)
• Mortar: 900 / 1000 x 0.5 = 0.45m3
• Cement bags at 1:5: approximately 0.45 / 0.12 = 4 bags cement
• Sand: approximately 20 bags soft sand (5 per cement bag)

Ordering in Practice

Bricks are typically sold in packs of 400-500 on a pallet. Always confirm pack quantities with your merchant before ordering - you will often need to round up to the nearest full pack. Delivery charges can make small top-up orders expensive, so it is worth ordering slightly more than your calculation on the first delivery.