Lumber Size Converter (Nominal to Actual)

A 2x4 isn’t 2 by 4 inches. Look up the actual size of dimensional lumber and boards in inches and mm.

How to use the Lumber Size Converter (Nominal to Actual)

Choose the nominal size.
Optionally enter a length.
Read the actual dimensions and board feet.

How it works

Nominal sizes describe rough-sawn green lumber. After drying and planing (surfacing), boards lose about ½ inch in thickness and width up to 6 inches, and ¾ inch on wider boards: a 2x4 is 1½″ × 3½″, a 2x6 is 1½″ × 5½″ and a 2x10 is 1½″ × 9¼″. Lengths are usually true or slightly long.

Nominal to actual

Nominal	Actual (in)	Actual (mm)
1x4	¾ × 3½	19 × 89
1x6	¾ × 5½	19 × 140
2x4	1½ × 3½	38 × 89
2x6	1½ × 5½	38 × 140
2x8	1½ × 7¼	38 × 184
2x10	1½ × 9¼	38 × 235
2x12	1½ × 11¼	38 × 286
4x4	3½ × 3½	89 × 89

Frequently asked questions

What is the actual size of a 2x4?

1½ × 3½ inches (38 × 89 mm).

Why is a 2x4 not 2 by 4?

The nominal size is before drying and planing.

What is the actual size of a 4x4?

3½ × 3½ inches.

What is the actual size of a 1x6?

¾ × 5½ inches.