Quick Answer
Actual Size of 2×4: 1.5 in × 3.5 in (38 mm × 89 mm)
A standard North American 2×4 finishes at an actual size of 1.5 inches by 3.5 inches, which is 38 mm by 89 mm.
“2×4” is the nominal label; drying and planing reduce it to the real dimensions shown here.
Exact measurements
| Label | Inches | Millimeters | Centimeters |
|---|---|---|---|
| Actual size of 2×4 | 1.5″ × 3.5″ | 38 × 89 | 3.8 × 8.9 |
| 2×4 width (real) | 3.5″ | 89 | 8.9 |
| 2×4 thickness (real) | 1.5″ | 38 | 3.8 |
Also searched as: 2×4 actual dimension, 2×4 true size, exact size of 2×4, and measurements of a 2×4.
Why “2×4” isn’t the actual size
“2×4” is the nominal size (rough-cut name). After kiln drying and planing (surfacing on four sides), the finished, usable board measures 1½″ × 3½″. This convention has been standard for decades in North American softwood framing lumber.
Related sizes
| Nominal | Actual (in) | Actual (mm) | More |
|---|---|---|---|
| 2×4 | 1.5 × 3.5 | 38 × 89 | 2×4 actual size (home) |
| 2×6 | 1.5 × 5.5 | 38 × 140 | 2×6 actual size |
| 2×8 | 1.5 × 7.25 | 38 × 184 | 2×8 actual size |
| 2×10 | 1.5 × 9.25 | 38 × 235 | 2×10 actual size |
| 4×4 | 3.5 × 3.5 | 89 × 89 | 4×4 actual size |
FAQ: Actual size of 2×4
What is the real size of a 2×4?
1.5 inches × 3.5 inches (38 × 89 mm). That’s the finished, surfaced size used in construction plans.
What is the 2×4 width?
The actual width is 3.5 inches (89 mm). The thickness is 1.5 inches (38 mm).
Is this the same everywhere?
For standard North American softwood framing lumber, yes. Rough-sawn or specialty lumber can differ slightly.