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Brick and mortar calculator
Estimate the number of bricks and mortar ingredients for a UK wall, after deducting door and window openings.
Your result
Your plan starts
with a few details.
Enter the wall dimensions, subtract any openings, and select Calculate to estimate materials.
How it works
Enter one wall length and height, the total area of any openings, and whether the wall is single skin or one brick thick. The calculator subtracts openings before estimating the bricks needed.
The brick count starts from 60 bricks per m² for single-skin stretcher bond or 120 per m² for one-brick-thick solid work. Choose a brick waste allowance, the cited merchant guide recommends 10% extra for breakage.
Choose a mortar supply estimate: 25 kg ready-mixed mortar bags, or the cited general-purpose site-mix recipe using cement, hydrated lime and building sand. Mortar estimates use the net wall brick count before extra bricks for breakage.
Formula
Gross wall area = wall length × wall height. Net wall area = gross wall area − total opening area.
Bricks to lay = net wall area × the selected bricks-per-m² rate, rounded up. Bricks to order = bricks to lay × (1 + waste allowance ÷ 100), rounded up.
Ready-mix bags = bricks to lay ÷ about 25 bricks per 25 kg bag, rounded up. For site mix, round up to whole batches of the cited recipe: each batch covers about 140 bricks and uses 25 kg cement × 1, 25 kg hydrated lime × 1, and building sand × 6 bags.
Worked example
For the cited-guide example of a 4 m × 0.5 m single-skin wall with no openings, gross and net area are 4 × 0.5 = 2 m². At 60 bricks/m², that is 120 bricks to lay. Add the entered 10% allowance: 120 × 1.1 = 132 bricks to order.
For the site-mix estimate, the 120 bricks to lay fit within the guide’s approximate 140-brick recipe: 1 × 25 kg cement, 1 × 25 kg hydrated lime and 6 bags of building sand. The guide does not specify the sand bag size.
Assumptions and limits
The cited guide uses a nominal 215 × 65 mm brick and 10 mm joints for its approximate count. Actual sizes, joint thickness, bond pattern, brick frogs and workmanship affect material use.
The source describes the mortar yields as approximate. Its site-mix example does not state the building sand bag mass or a finished mortar volume, so the result is only a count of sand bags with no assumed bag size or m³ conversion.
Mortar choice and strength must suit the wall, exposure and design. The cited 6:1:1 recipe is a general-purpose estimating example, not a structural mortar specification. Follow the project design and supplier or designer instructions.
Opening area is subtracted once from the measured wall face. Returns, reveals, lintels, piers, corners, special bricks, bond changes, delivery packs and mortar loss are not modelled. Ask a brick supplier or qualified professional to check large or structural orders.
Frequently asked questions
How many bricks do I need per square metre?
The cited UK guide allows about 60 bricks per m² for single-skin stretcher bond and 120 per m² for a one-brick-thick solid wall. Add an allowance for cuts and breakage.
How much mortar do I need for 1,000 bricks?
The merchant guide estimates about 25 bricks from one 25 kg ready-mix bag. For a site mix, its general-purpose recipe says one 25 kg cement bag, one 25 kg hydrated lime bag and six bags of building sand lay about 140 bricks. These are approximate yields, and the sand bag size is not specified.
Does the calculator account for doors and windows?
Yes. Enter their combined face area, that area is subtracted from the gross wall area before estimating bricks and mortar.
Does the quantity include bricks for returns and corners?
Only the measured wall face area and entered allowance are counted. Add returns, piers and other wall faces to the measured area and plan special cuts separately.
Sources
Specs as of: