Lumber size chart: nominal vs actual
What every common piece of softwood actually measures, against what it is called. A 2x4 is 1 1/2" by 3 1/2", and every cut list that assumes otherwise is wrong by the time it reaches the saw.
| Called | Actual thickness | Actual width | Cross-section | Lost to dressing |
|---|---|---|---|---|
| 1x2 | 3/4" | 1 1/2" | 1.13 in² | 1/4" × 1/2" |
| 1x3 | 3/4" | 2 1/2" | 1.88 in² | 1/4" × 1/2" |
| 1x4 | 3/4" | 3 1/2" | 2.63 in² | 1/4" × 1/2" |
| 1x6 | 3/4" | 5 1/2" | 4.13 in² | 1/4" × 1/2" |
| 1x8 | 3/4" | 7 1/4" | 5.44 in² | 1/4" × 3/4" |
| 1x10 | 3/4" | 9 1/4" | 6.94 in² | 1/4" × 3/4" |
| 1x12 | 3/4" | 11 1/4" | 8.44 in² | 1/4" × 3/4" |
| 5/4x6 | 1" | 5 1/2" | 5.50 in² | 1/4" × 1/2" |
| 2x2 | 1 1/2" | 1 1/2" | 2.25 in² | 1/2" × 1/2" |
| 2x3 | 1 1/2" | 2 1/2" | 3.75 in² | 1/2" × 1/2" |
| 2x4 | 1 1/2" | 3 1/2" | 5.25 in² | 1/2" × 1/2" |
| 2x6 | 1 1/2" | 5 1/2" | 8.25 in² | 1/2" × 1/2" |
| 2x8 | 1 1/2" | 7 1/4" | 10.88 in² | 1/2" × 3/4" |
| 2x10 | 1 1/2" | 9 1/4" | 13.88 in² | 1/2" × 3/4" |
| 2x12 | 1 1/2" | 11 1/4" | 16.88 in² | 1/2" × 3/4" |
| 4x4 | 3 1/2" | 3 1/2" | 12.25 in² | 1/2" × 1/2" |
| 4x6 | 3 1/2" | 5 1/2" | 19.25 in² | 1/2" × 1/2" |
Reading it
- Dry, surfaced-four-sides sizes from US Department of Commerce PS 20, the American Softwood Lumber Standard.
- The rule that reproduces the table: 1/4" off a nominal thickness under 2" and 1/2" from 2" through 4"; 1/2" off a width up to a nominal 6" and 3/4" from a nominal 8" up. The break in the width rule is at eight inches, not six.
- Green lumber is allowed to be slightly larger because it has not finished shrinking. Rough-sawn is whatever the mill left it — measure it.
- Hardwood is not sold this way. It is sold rough by the quarter and priced by the board foot.
For the case this table does not cover
- Board foot calculator
How much lumber to buy for a finished piece, what it will cost, and what to ask for at the yard.
- Board cut calculator
How many pieces of one length come out of a board of another, with the kerf charged between cuts and the leftover shown.
- Wall framing stud count
Field studs at 16" or 24" on centre, corner studs, and the king and jack studs every opening adds.