Quick Answer
2×4 Measurements: 1.5″ × 3.5″ (38 mm × 89 mm)
The **measurements** of a standard surfaced 2×4 are 1.5 inches thick by 3.5 inches wide.
In metric terms, this equals 38 mm × 89 mm. Lengths vary—common options are 8′, 10′, 12′, and more.
Nominal vs actual measurements
The 2×4’s name comes from its nominal size—its rough-sawn dimension before drying and planing. Once processed, the actual measurement becomes 1.5″ × 3.5″.
Measurements in all units
| Dimension | Inches | Millimeters | Centimeters |
|---|---|---|---|
| Thickness | 1.5″ | 38 | 3.8 |
| Width | 3.5″ | 89 | 8.9 |
Minor variations can occur from manufacturing tolerances and moisture changes.
FAQ: 2×4 measurements
Are measurements the same for all 2×4 lumber?
Yes for surfaced lumber in North America, but raw or specialty cuts can differ.
Do treated 2×4s measure differently?
No—the standard 1.5″ × 3.5″ applies, though treated boards may temporarily swell if wet.