Reference chart
Lumber Dimensions Chart
What a 2x4 really measures. Nominal vs actual surfaced softwood sizes, plus hardwood 4/4 quarter stock and its surfaced thickness.
Lumber is sold by a nominal size that is larger than the finished board: the difference is the wood removed when the rough lumber is dried and surfaced. A 2x4 actually measures 1-1/2 by 3-1/2 inches.
Softwood (S4S, dry)
| Nominal | Actual (in) |
|---|---|
| 1 x 2 | 3/4 x 1-1/2 |
| 1 x 3 | 3/4 x 2-1/2 |
| 1 x 4 | 3/4 x 3-1/2 |
| 1 x 6 | 3/4 x 5-1/2 |
| 1 x 8 | 3/4 x 7-1/4 |
| 1 x 10 | 3/4 x 9-1/4 |
| 1 x 12 | 3/4 x 11-1/4 |
| 2 x 2 | 1-1/2 x 1-1/2 |
| 2 x 4 | 1-1/2 x 3-1/2 |
| 2 x 6 | 1-1/2 x 5-1/2 |
| 2 x 8 | 1-1/2 x 7-1/4 |
| 2 x 10 | 1-1/2 x 9-1/4 |
| 2 x 12 | 1-1/2 x 11-1/4 |
| 4 x 4 | 3-1/2 x 3-1/2 |
| 6 x 6 | 5-1/2 x 5-1/2 |
Hardwood quarter stock
Hardwood thickness is called out in quarters of an inch of rough thickness; surfaced two sides (S2S) it ends up thinner.
| Call | Rough (in) | Surfaced S2S (in) |
|---|---|---|
| 4/4 | 1 | 13/16 |
| 5/4 | 1-1/4 | 1-1/16 |
| 6/4 | 1-1/2 | 1-5/16 |
| 8/4 | 2 | 1-3/4 |
| 12/4 | 3 | 2-3/4 |
| 16/4 | 4 | 3-3/4 |
Hardwood board feet are billed on the rough thickness (so 4/4 counts as 1 inch) even after surfacing.
Related calculators
Sources
These calculators are for planning and estimation. Engineering results (shelf sag, wood movement) use published average material properties; real boards vary by grade, grain, moisture and defects. Verify load-bearing designs with a professional.