2×4 Dim (Dimensions) – Quick Answer
When people search “2×4 dim” they want the real, finished dimensions. A standard North American 2×4 (kiln-dried, surfaced) measures 1.5 inches by 3.5 inches. In metric, that is 38 mm by 89 mm.
Quick Specs
2×4 actual dim: 1.5 in × 3.5 in (38 mm × 89 mm)
2×4 nominal dim: 2 in × 4 in (rough-cut label before drying/planing)
Exact Dimensions Table
| Dimension | Inches (Actual) | Millimeters | Centimeters |
|---|---|---|---|
| Thickness | 1.5 | 38 | 3.81 |
| Width | 3.5 | 89 | 8.89 |
Why “Dim” Differs from the Name
“2×4” is the nominal size. After the board is kiln-dried and planed smooth (S4S), material is removed from each face, giving the actual dim of 1.5″ × 3.5″ used in construction plans and code tables.
Conversions
- Inches to mm:
mm = inches × 25.4 - 1.5 × 25.4 = 38.1 → 38 mm (rounded)
- 3.5 × 25.4 = 88.9 → 89 mm (rounded)
Related Pages
- 2×4 actual dimension
- 2×4 width: 3.5 inches (89 mm)
- 2×4 in mm: 38 × 89 • 2×4 in cm: 3.81 × 8.89
- 2×4 measurements (all units)
FAQ: 2×4 Dim
Are all 2×4 dims exactly 1.5 × 3.5?
For surfaced framing lumber in the U.S./Canada, yes—allowing for small mill and moisture tolerances.
Do treated 2x4s have different dims?
No. They’re surfaced to the same finished size; freshly treated boards may shrink slightly as they dry.
What about rough-sawn 2x4s?
Rough-sawn (unsurfaced) pieces can be closer to nominal, around 1.75 × 3.75. Retail framing lumber is typically 1.5 × 3.5.
Key Takeaway
2×4 dim = 1.5″ × 3.5″ (38 × 89 mm). Plan your cuts and layouts with the actual dimensions, not the nominal label.