2x4s are not actually 2 inches by 4 inches.
When the board is first rough sawn from the log, it is
a true 2x4, but the drying process and planing of the
board reduce it to the finished 1.5x3.5 size.
Here are the common sizes of lumber, and their actual sizes.
|
Nominal |
Actual |
Actual - Metric |
|
1" x 2" |
3/4" x 1-1/2" |
19 x 38 mm |
|
1" x 3" |
3/4" x 2-1/2" |
19 x 64 mm |
|
1" x 4" |
3/4" x 3-1/2" |
19 x 89 mm |
|
1" x 5" |
3/4" x 4-1/2" |
19 x 114 mm |
|
1" x 6" |
3/4" x 5-1/2" |
19 x 140 mm |
|
1" x 7" |
3/4" x 6-1/4" |
19 x 159 mm |
|
1" x 8" |
3/4" x 7-1/4" |
19 x 184 mm |
|
1" x 10" |
3/4" x 9-1/4" |
19 x 235 mm |
|
1" x 12" |
3/4" x 11-1/4" |
19 x 286 mm |
|
1-1/4" x 4" |
1" x 3-1/2" |
25 x 89 mm |
|
1-1/4" x 6" |
1" x 5-1/2" |
25 x 140 mm |
|
1-1/4" x 8" |
1" x 7-1/4" |
25 x 184 mm |
|
1-1/4" x 10" |
1" x 9-1/4" |
25 x 235 mm |
|
1-1/4" x 12" |
1" x 11-1/4" |
25 x 286 mm |
|
1-1/2" x 4" |
1-1/4" x 3-1/2" |
32 x 89 mm |
|
1-1/2" x 6" |
1-1/4" x 5-1/2" |
32 x 140 mm |
|
1-1/2" x 8" |
1-1/4" x 7-1/4" |
32 x 184 mm |
|
1-1/2" x 10" |
1-1/4" x 9-1/4" |
32 x 235 mm |
|
1-1/2" x 12" |
1-1/4" x 11-1/4" |
32 x 286 mm |
|
2" x 4" |
1-1/2" x 3-1/2" |
38 x 89 mm |
|
2" x 6" |
1-1/2" x 5-1/2" |
38 x 140 mm |
|
2" x 8" |
1-1/2" x 7-1/4" |
38 x 184 mm |
|
2" x 10" |
1-1/2" x 9-1/4" |
38 x 235 mm |
|
2" x 12" |
1-1/2" x 11-1/4" |
38 x 286 mm |
|
3" x 6" |
2-1/2" x 5-1/2" |
64 x 140 mm |
|
4" x 4" |
3-1/2" x 3-1/2" |
89 x 89 mm |
|
4" x 6" |
3-1/2" x 5-1/2" |
89 x 140 mm |