Lumber Dimensions Chart

Lumber is sold by its nominal size, but the actual milled dimensions are smaller. A “2×4” is really 1.5 by 3.5 inches. Here is the full nominal-to-actual chart.

Nominal Actual (in)
1×2 3/4 x 1-1/2
1×4 3/4 x 3-1/2
1×6 3/4 x 5-1/2
1×8 3/4 x 7-1/4
1×10 3/4 x 9-1/4
1×12 3/4 x 11-1/4
2×2 1-1/2 x 1-1/2
2×4 1-1/2 x 3-1/2
2×6 1-1/2 x 5-1/2
2×8 1-1/2 x 7-1/4
2×10 1-1/2 x 9-1/4
2×12 1-1/2 x 11-1/4
4×4 3-1/2 x 3-1/2
6×6 5-1/2 x 5-1/2
Why the difference? Nominal is the rough-sawn size; the board is then dried and planed smooth, removing material. Boards 8 in and wider lose 3/4 in rather than 1/2 in.

See the 2×4 actual dimensions and the Plywood Sizes Chart.

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