UK brick

A standard UK brick measures 8.46 inches (215 mm) long, 4.03 inches (102.5 mm) wide, and 2.56 inches (65 mm) tall. This is the coordinating size defined by British Standard BS EN 771, used throughout the UK and much of the Commonwealth for residential and commercial masonry. This page covers the exact dimensions, mortar joint conventions, and how UK brick compares to the US standard.

Dimensions

Coordinating vs work size

The 215 x 102.5 x 65 mm dimensions above are the “work size,” the brick’s actual physical measurement. The “coordinating size,” which includes a standard 10 mm mortar joint, is 225 x 112.5 x 75 mm, designed so bricks plus joints align cleanly to a 75 mm vertical module and 225 mm horizontal module.

UK brick sizing history

The UK brick size was standardized in metric units in the 1960s and 1970s as the country transitioned from imperial measurements. The dimensions were chosen to closely match the size and proportions of the older imperial brick (about 8.625 x 4.125 x 2.625 inches), easing the transition for the construction industry.

Mortar joint standards

UK masonry conventionally uses a 10 mm mortar joint, slightly larger than the 3/8 inch (9.5 mm) joint common in the US. This is factored into the coordinating size system so that a specific number of bricks plus joints reaches standard measurements like 225 mm or 675 mm, simplifying wall layout for UK builders.

UK brick vs US brick

A UK brick is larger than a US brick in every dimension, about 12 mm longer, 10.5 mm wider, and 8 mm taller. This means bricks and building plans are not directly interchangeable between the two countries, and imported bricks from one system generally cannot substitute for the other without adjusting the overall design.

Weight

A standard UK brick weighs approximately 5.5 to 6.6 pounds (2.5 to 3 kg), somewhat heavier than a comparable US brick due to its larger overall size.

Frequently asked questions

What is the standard size of a UK brick?

215 x 102.5 x 65 mm (8.46 x 4.03 x 2.56 inches) for the work size, or 225 x 112.5 x 75 mm coordinating size including a standard mortar joint.

How much does a UK brick weigh?

About 2.5 to 3 kg (5.5 to 6.6 pounds), depending on the specific clay composition and manufacturing process.

Is a UK brick bigger than a US brick?

Yes. A UK brick is larger in every dimension than a standard US brick, which measures 203 x 92 x 57 mm compared to the UK’s 215 x 102.5 x 65 mm.

What mortar joint size does UK construction use?

10 mm is the standard mortar joint in UK masonry, slightly larger than the roughly 9.5 mm joint typically used in US construction.

Why is the UK brick size metric?

The UK converted its brick standard to metric measurements in the 1960s and 1970s during the country’s broader shift to the metric system, while keeping the new dimensions close to the older imperial brick size.

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