How to Measure a Brick Correctly

Accurate dimensions are one of the most useful pieces of information you can provide when identifying a brick. A brick that looks similar in a photograph may belong to a different product range once its actual dimensions are known.

The three measurements

Record length × width × height, preferably in millimetres. Length is the longest dimension, height is the vertical dimension when the brick is laid normally, and width is the depth through the wall. State the order clearly so another person can reproduce your measurement.

Measure the brick, not the mortar

Do not measure from the edge of one mortar joint to the next and call that the brick size. Mortar joints vary. The joint can also be recessed, weathered or over-pointed, making an apparent brick dimension misleading.

Measure several bricks

Older and reclaimed bricks may have chipped corners, worn faces or dimensional variation. If possible, measure three or more accessible examples. Record the individual readings rather than automatically rounding them to a familiar nominal size.

What if the brick is in a wall?

Use an exposed face and choose a brick with intact edges where practical. A tape measure or small ruler can work, while a loose brick can be measured on a flat surface. Do not remove a brick from a wall simply for identification if doing so could damage the building or compromise masonry.

Common mistakes

• Including the mortar joint.
• Measuring a damaged corner as though it were the original edge.
• Confusing brick height with width.
• Using a photograph to estimate dimensions without a scale reference.
• Assuming every brick in an old wall has identical dimensions.

Use dimensions with other evidence

Dimensions are powerful but not unique. Several manufacturers can produce bricks with similar nominal sizes. Combine measurements with colour, texture, manufacturing method, frog, maker's mark and architectural context.

Use Find My Brick and enter the measurements if the tool asks for them. For replacement work, confirm the dimensions of a physical sample before ordering.