1x8 actual size
¾ × 7¼ inches
1.9 × 18.4 cm · 19 × 184 mm · sold as a 1x8
Nominal against actual
| Nominal | Actual | Difference | |
|---|---|---|---|
| Thickness | 1 in | ¾ in (19 mm) | −¼ in |
| Width | 8 in | 7¼ in (184 mm) | −¾ in |
| Cross-section | 8 in² | 5.44 in² | −32% |
What a 1x8 is for
Shelving, rough-sawn siding and the wide boards in a plank table. Note the extra ¼ inch it loses — 8 inches nominal is where the rule changes.
The name is the rough-sawn size before drying and planing. Why every board is smaller than its name →
What this costs you in practice
The error compounds wherever boards sit side by side. Three 1x8s are 21¾ inches across, not 24; eight of them are 58 inches rather than 64, which is 6 inches short over a run you might have measured on paper. That is why framing is dimensioned centre to centre and not edge to edge: 16 inches on centre is a real 16 inches whatever the boards themselves measure, so a sheet of plywood still lands on a stud.
Other 1-inch nominal boards
| Nominal | Actual | In mm |
|---|---|---|
| 1x2 | ¾ × 1½ in | 19 × 38 mm |
| 1x3 | ¾ × 2½ in | 19 × 64 mm |
| 1x4 | ¾ × 3½ in | 19 × 89 mm |
| 1x6 | ¾ × 5½ in | 19 × 140 mm |
| 1x10 | ¾ × 9¼ in | 19 × 235 mm |
| 1x12 | ¾ × 11¼ in | 19 × 286 mm |
Frequently asked questions
What is the actual size of a 1x8?
¾ × 7¼ inches — 1.9 × 18.4 cm, or 19 × 184 mm.
Why is a 1x8 not 1 by 8 inches?
Because it was, once. The board is sawn at roughly its nominal size while green, then dried and planed smooth on all four faces, and both processes take material off. The name records the rough-sawn size and the label never caught up. This is standardised, not accidental — every mill in North America surfaces to the same finished dimensions.
How much smaller is a 1x8 than its name?
¼ inch off the thickness and ¾ off the width, which is 32% less cross-section than the name implies. That matters for spans and for anything where you are counting boards to fill a width.
What lengths does a 1x8 come in?
Typically 6, 8, 10, 12, 14, 16, 20 feet. Unlike the cross-section, length is not reduced — an 8-foot board is 8 feet, or a little over, because it is cut to length after planing.