Inch to Millimeter
1 in = 25.4 mm
Convert Inch (in) to Millimeter (mm) with engineering-grade precision. Instant results, formula, and reference table below.
1 Inch ≈25.4 Millimeter
How to convert Inch to Millimeter (in to mm)
Converting Inchs to Millimeters is critical for developers working with international data standards or scientific applications. This tool performs the calculation entirely on your client (browser) using JavaScript/WASM, ensuring zero latency and maximum privacy.
The Formula
1 in = 25.4000 mm
Calculation Example
Let's say you want to convert 5 in to mm:
- Input: 5 in
- Calculation: 5 × 25.4000
- Result: 127.0000 mm
About the Inch to Millimeter conversion
The conversion factor from Inch (in) to Millimeter (mm) is 25.4, meaning 1 in = 25.4 mm and inversely 1 mm = 0.03937 in. That makes the Inch the larger of the two units in the length category, where the SI base unit is the meter. Every ratio here is derived from the SI/international definition rather than a rounded approximation, so results are stable across repeated conversions.
Need the reverse? Use the Millimeter to Inch converter.
Frequently Asked Questions
How do I convert Inch to Millimeter?
To convert Inch to Millimeter, you need to multiply the in value by 25.4000.
What is the formula for in to mm?
The simple formula is: mm = in × 25.4000.
Which is bigger: Inch or Millimeter?
A Inch is bigger. One Inch is equal to approx 25.4000 Millimeters.
How many Inchs are in one Millimeter?
There are approximately 0.0393701 Inchs in one Millimeter.
Quick Conversion Table
| in | mm |
|---|---|
| 1 | 25.4000 |
| 5 | 127.0000 |
| 10 | 254.0000 |
| 20 | 508.0000 |
| 50 | 1270.0000 |
| 100 | 2540.0000 |