1 Inches to Millimeters
1 Inches in Millimeters
25.4 Millimeters
1 Inches = 25.4 Millimeters
1 inches is equal to 25.4 millimeters.
Quick reference
More length conversions
Millimeters → Inches
Kilometers → MilesMiles → KilometersCentimeters → InchesInches → CentimetersFeet → MetersMeters → FeetMillimeters → Inches All converters
Frequently asked questions
What is the exact formula for Inches to Millimeters?
Multiply the Inches value by 25.4. This comes from the exact unit definitions, not a rounded approximation.
Is this conversion exact?
The underlying ratio is exact where a legal definition exists (for example, 1 inch = 25.4 mm exactly). Displayed results are rounded to six decimal places for readability.
Can I convert Millimeters back to Inches?
Yes. Use the reverse converter linked below, or just swap which field you type into: the live converter recalculates either direction.