Construction material dimensions guide

Actual size is the manufactured or measured piece; nominal size is its trade designation. A coordinating size adds the chosen joint allowance. The table adds exactly one entered joint to each actual dimension; it does not assume that every nominal designation equals actual plus joint.

A common UK brick is 215 × 102.5 × 65 mm; adding 10 mm gives a coordinating size of 225 × 112.5 × 75 mm. Acme modular brick is 7⅝ × 3⅝ × 2¼ inches. The illustrated CMHA nominal 12 × 8 × 16-inch block has actual width 11⅝, height 7⅝ and length 15⅝ inches. Dry surfaced nominal 2×4 lumber is commonly 1½ × 3½ inches; measure the supplied product.

Crown face width, ceiling projection and wall height are different measurements. Ekena WM291 lists a 5¼-inch face, 3½-inch projection and 4-inch height. Use the exact profile drawing and spring angle when selecting or cutting crown; a face width alone does not determine the installed dimensions.

Reference: UK brick dimensions · Reference: Acme modular brick · Reference: CMHA block dimensions · Reference: US softwood lumber · Reference: Ekena crown dimensions

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The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Dimension reference

UK standard brick example

Entered joint allowance

10 mm

Primary result: Actual width: 102.5 mm.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

Examples are product- and region-specific, not universal sizes. Manufacturer tolerances, moisture condition, mortar specification and existing construction can change actual dimensions. This guide does not certify a structural, fire or acoustic assembly. Check current product documentation before ordering.