Fraction to mm Calculator
Convert any fraction of an inch to millimeters instantly. Perfect for machining, woodworking, 3D printing, and engineering.
Step 1: Enter Fraction
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📐 Conversion formula
1 inch = 25.4 mm exactly. To convert: inches (as decimal) × 25.4 = mm.
Step 2: Options
⚙️ Precision tip
For engineering work, 3-4 decimals are recommended. 1/64 inch ≈ 0.397 mm.
Conversion Result
Result
Common Fractions
Formula & Info
Millimeters
12.70
1/2 inch = 12.70 mm
Decimal inches
0.5
Fraction (simplified)
1/2
mm (rounded)
12.7
1 inch reference
25.4 mm
Common Fractions to mm
| Fraction (inches) | Decimal inches | Millimeters (2 dec) |
|---|
Conversion Formula
📏 Inches to Millimeters
mm = inches × 25.4
Where inches can be a fraction or decimal. Example: 3/8 = 0.375 in → 0.375 × 25.4 = 9.525 mm.
The inch is defined as exactly 25.4 mm since 1959.
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