Precision Conversion Tool

MM TO INCHES
CONVERTER

Instant, accurate millimeter to inch conversions — including fractional inches. Built for engineers, woodworkers, machinists, and makers across the USA.

25.4
mm per inch
±0
rounding error
1/64"
finest fraction
∞
conversions free
Live Converter
// Type in either field — converts instantly in real time
Millimeters (mm)
mm
Enter a value above
=
⇄
=
Inches (in)
in
Enter a value above
Visual Scale (0 → 300 mm / 0 → 11.81 in) 0%
030mm / 1.18"60mm / 2.36"90mm / 3.54" 120mm / 4.72"150mm / 5.91"200mm / 7.87"300mm / 11.81"
—
Millimeters
—
Decimal Inches
—
Fractional Inches
Batch Converter
// Convert multiple values at once — one per line
Input — mm values (one per line)
Results — inches (decimal & fraction)
Results appear here...
Quick Reference
// Common conversions used in US manufacturing & construction
Full Reference Table
// mm to inches — decimal and fractional
Millimeters (mm) Decimal Inches Fractional Inches Centimeters Common Use
Formulas & Method
// Exact conversion factors used by this tool
MM → Inches (Decimal)
inches = mm ÷ 25.4
1 inch = 25.4 mm exactly (defined by international agreement since 1959)
Inches → MM
mm = inches × 25.4
Multiply by 25.4 to go from inches back to millimeters
Fractional Inches Conversion
closest = round(decimal × denominator) / denominator
Supported denominators: 2, 4, 8, 16, 32, 64 — select based on required precision
Example: 50mm → Inches
50 ÷ 25.4 = 1.9685" ≈ 1 31/32"
Nearest 1/16": 2", nearest 1/32": 1 31/32", nearest 1/64": 1 63/64"
FAQ
// Frequently asked conversion questions
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