What this calculator works out
This calculator works out the net wall area after deducting openings, multiplies by the bricks per square metre, and adds a waste allowance.
The bricks-per-square-metre figure decides everything. Sixty is the standard figure for a single-skin wall in UK bricks; a solid one-brick wall needs 120, and getting that wrong halves or doubles the order.
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Before you order
- Sixty bricks per square metre applies to a half-brick, single-skin wall using standard 215 by 102.5 by 65 mm bricks with 10 mm joints.
- A one-brick solid wall, or a cavity wall counted as both skins, needs 120 per square metre.
- Enter openings as a total area in square metres, not as a count.
- Allow 5% waste for straightforward work and 10% or more where there are cuts, returns or a decorative bond.
A standard brick face with its mortar joints occupies 225 mm by 75 mm, which is 0.016875 m². One square metre divided by that is 59.3, rounded to 60. That is why the figure holds only for standard UK bricks at standard joint thickness — metric or imperial-sized bricks give a different number.
How this calculator works
Net area, then quantity:
Net wall area = (length × height) − openings area
Bricks before waste = net area × bricks per m²
Total = bricks before waste × (1 + waste ÷ 100), rounded upMortar is not calculated here. As a guide, a single-skin wall uses roughly 0.03 m³ of mortar per square metre, which is around one 25 kg bag of cement per 12 to 15 m² at a 1:5 mix.
Worked example: a 5 m by 2 m wall
Using the default figures — 5 m long, 2 m high, no openings, 60 bricks per m², 10% waste:
- Net wall area: 10 m²
- Before waste: 10 × 60 = 600 bricks
- Total to order: 660 bricks
If that wall were a solid one-brick wall rather than single skin, the same 10 m² would need 1,320 bricks — and the foundation, which is sized to the wall it carries, would need to be wider too. Establishing which construction you are building before ordering is more consequential than the waste allowance.
Common mistakes
- Using 60 per m² for a cavity or solid wall. Both skins together need 120.
- Entering openings as a count instead of an area. The field expects square metres.
- Ordering from more than one batch. Brick colour varies between batches and the difference shows.
- Forgetting mortar, wall ties, DPC and lintels. None are included in the brick count.
- Building a garden wall without checking foundations and height limits.
Frequently asked questions
How many bricks are in a pack?
Commonly 400 to 500, depending on the manufacturer and brick type. Packs are heavy — around a tonne — and need thinking about for delivery access and where they will be stacked. Buying by the pack rather than the exact count usually costs little more and avoids running short.
Do I need building regulations approval for a garden wall?
Freestanding garden walls are generally exempt from building regulations but are subject to planning height limits — usually 1 metre next to a highway and 2 metres elsewhere, though this varies and listed buildings and conservation areas differ. A retaining wall holding back ground is a different matter and may need proper design.
How much mortar will I need?
Roughly 0.03 m³ per square metre of single-skin wall, or about a tonne of sand and six bags of cement per 25 to 30 m². Mortar mixes are typically 1:5 or 1:6 cement to building sand, sometimes with plasticiser or lime. Weaker mixes are usually better than stronger ones for garden walls, since they accommodate movement.
What is frost resistance and why does it matter?
UK bricks are classified F2 (freeze/thaw resistant), F1 (moderately resistant) or F0 (not resistant). Anything exposed to weather, and particularly anything below damp-proof course level or in a garden wall, should be F2. Using an unsuitable brick outdoors leads to spalling faces within a few winters.
Is what I enter stored?
No. Measurements are processed in your browser and never transmitted or retained.
Related tools
References
- GOV.UK — planning rules on boundary walls and building regulations guidance
- Health and Safety Executive — manual handling of bricks and blocks, and cement safety
Sources are checked at publication and can change — how I choose and check references.