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Nominal/Actual Sizes

Nominal vs. Actual Lumber Size Tables

North America lumber sizes are usually given in "nominal" measurements, which is the size of lumber cut from moist logs. However, the actual size of lumber is less than its nominal size (due to shrinkage and surface planning at mills). The table below provides some common North American Lumber nominal sizes and their equivalent actual size.

For example, 1x8 actual size is 3/4" x 7-1/4", and 2 x 12 actual size is 1-1/2" x 11-1/4", and 2x 10 actual size is 1-1/2" x 9-1/4".

Nominal Size Standard Dressed Size
in. x in.
Standard Dressed Size
mm x mm
Area of Section
in.2
Boards
1 x 3 3/4 x 2-1/2 19 x 63 1.875
1 x 4 3/4 x 3-1/2 19 x 89 2.625
1 x 6 3/4 x 5-1/2 19 x 140 3.781
1 x 8 3/4 x 7-1/4 19 x 184 5.438
1 x 10 3/4 x 9-1/4 19 x 235 6.938
1 x 12 3/4 x 11-1/4 19 x 286 8.438
Dimension Lumber and Decking
2 x 3 1-1/2 x 2-1/2 38 x 64 3.750
2 x 4 1-1/2 x 3-1/2 38 x 89 5.250
2 x 5 1-1/2 x 4-1/2 38 x 114 6.750
2 x 6 1-1/2 x 5-1/2 38 x 140 8.250
2 x 8 1-1/2 x 7-1/4 38 x 184 10.88
2 x 10 1-1/2 x 9-1/4 38 x 235 13.88
2 x 12 1-1/2 x 11-1/4 38 x 286 16.88
2 x 14 1-1/2 x 13-1/4 38 x 337 19.88
3 x 4 2-1/2 x 3-1/2 64 x 89 8.75
3 x 5 2-1/2 x 4-1/2 64 x 114 11.25
3 x 6 2-1/2 x 5-1/2 64 x 140 13.75
3 x 8 2-1/2 x 7-1/4 64 x 184 18.13
3 x 10 2-1/2 x 9-1/4 64 x 235 23.13
3 x 12 2-1/2 x 11-1/4 64 x 286 28.13
3 x 14 2-1/2 x 13-1/4 64 x 337 33.13
3 x 16 2-1/2 x 15-1/4 64 x 387 38.13
4 x 4 3-1/2 x 3-1/2 89 x 89 12.25
4 x 5 3-1/2 x 4-1/2 89 x 114 15.75
4 x 6 3-1/2 x 5-1/2 89 x 140 19.25
4 x 8 3-1/2 x 7-1/4 89 x 184 25.38
4 x 10 3-1/2 x 9-1/4 89 x 235 32.38
4 x 12 3-1/2 x 11-1/4 89 x 286 39.38
4 x 14 3-1/2 x 13-1/4 89 x 337 46.38
4 x 16 3-1/2 x 15-1/4 89 x 387 53.38
Post and Timber
5 x 5 4-1/2 x 4-1/2 114 x 114 20.25
6 x 6 5-1/2 x 5-1/2 140 x 140 30.25
6 x 8 5-1/2 x 7-1/2 140 x 190 41.25
8 x 8 7-1/2 x 7-1/2 190 x 190 56.25
8 x 10 7-1/2 x 9-1/2 190 x 241 71.25
10 x 10 9-1/2 x 9-1/2 241 x 241 90.25
10 x 12 9-1/2 x 11-1/2 241 x 292 109.3
12 x 12 11-1/2 x 11-1/2 292 x 292 132.3
12 x 14 11-1/2 x 13-1/2 292 x 343 155.3
14 x 14 13-1/2 x 13-1/2 343 x 343 182.3
14 x 16 13-1/2 x 15-1/2 343 x 394 209.3




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