Measurement Tutorials March 14, 2026 ⏱ 5 min read

Metric vs Imperial Lumber Conversions

🔄METRICmm · cm · m⟷IMPERIALin · ft · yd1 inch = 25.4 mm  |  1 foot = 304.8 mm  |  1 meter = 3.281 ft

International lumber orders, imported sheet goods, and woodworking plans from different countries all require quick and accurate unit conversion. This guide gives you the essential formulas and tables.

Core Conversion Factors

FromToMultiply by
InchesMillimeters25.4
MillimetersInches0.03937
FeetMeters0.3048
MetersFeet3.2808
InchesCentimeters2.54
CentimetersInches0.3937
Board FeetCubic Meters0.002360
Cubic MetersBoard Feet423.776

Common Lumber Sizes: Metric ↔ Imperial

Imperial (nominal)Imperial (actual)Metric Equivalent
1 × 43/4” × 3-1/2”19 × 89 mm
1 × 63/4” × 5-1/2”19 × 140 mm
2 × 41-1/2” × 3-1/2”38 × 89 mm
2 × 61-1/2” × 5-1/2”38 × 140 mm
2 × 81-1/2” × 7-1/4”38 × 184 mm
2 × 101-1/2” × 9-1/4”38 × 235 mm
2 × 121-1/2” × 11-1/4”38 × 286 mm
4 × 43-1/2” × 3-1/2”89 × 89 mm

Conversion Examples

Example 1 — European Plan to Imperial

Plan calls for a shelf: 600mm × 300mm × 18mm

Length: 600 ÷ 25.4 = 23.6 inches

Width: 300 ÷ 25.4 = 11.8 inches

Thickness: 18 ÷ 25.4 = 0.71 inches (≈ 3/4”)

Example 2 — Board Feet to Cubic Meters

You need 500 board feet for an export order quoted in m³.

500 × 0.002360 = 1.18 cubic meters

💡 Pro Tip: When ordering from European or Asian suppliers, always confirm whether dimensions are given in actual or nominal sizes. Metric lumber is typically sold at actual dimensions, unlike North American nominal sizing.

Frequently Asked Questions

Is a 2×4 really 2 inches by 4 inches?

No. North American softwood lumber uses nominal sizes that are larger than the actual dimensions. A “2×4” actually measures 1-1/2” × 3-1/2” (38 × 89 mm) after drying and planing.

How do I convert cubic meters to board feet?

Multiply cubic meters by 423.776. For example, 2.5 m³ × 423.776 = 1,059.44 board feet. Use our Board Foot to Cubic Meter calculator for instant results.

Why do some countries use different lumber sizes?

Lumber sizing standards vary by country. Canada and the US use the nominal system. European and Australian lumber follows actual metric dimensions. Japanese lumber has its own size standards (shaku/sun). Always verify the standard being used.

Convert Measurements Instantly

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