2×4 Actual Size and Exact Measurements
If you have ever picked up a 2×4 from the lumber aisle, you might have noticed something surprising — it is not actually 2 inches by 4 inches. The “2×4” label refers to its nominal size, not the real-world measurement. Here’s the accurate breakdown so you always know exactly what you’re working with.
Exact Measurements
Standard U.S. 2×4 (kiln-dried):
Actual Size: 1.5 inches by 3.5 inches
Metric: 38 mm by 89 mm
Centimeters: 3.8 cm by 8.9 cm
Nominal vs. Actual Size
The nominal size (2 inches by 4 inches) is the rough-cut dimension before the wood is dried and planed. Once processed, the dimensions shrink to the actual size.
2×4 Size Table
| Type | Inches (Actual) | Millimeters | Centimeters |
|---|---|---|---|
| Standard 2×4 | 1.5 × 3.5 | 38 × 89 | 3.8 × 8.9 |
| Green/Unsurfaced 2×4 | 1.75 × 3.75 | 44 × 95 | 4.4 × 9.5 |
Why Knowing the Exact Size Matters
- Ensures accurate cuts and fitting for construction projects.
- Helps with material planning and estimating quantities.
- Prevents costly mistakes when building furniture or framing walls.
International Notes
In Canada, the U.S. dimensions are usually followed. In the UK, Australia, and other countries, dimensions may vary slightly due to local milling standards.
Final Tip
Always measure lumber before starting your project — even “standard” sizes can vary slightly between mills and batches.