Inches to Millimeters (in to mm) Converter
1 inch (in) = 25.4 millimeters (mm). To convert inches to millimeters, multiply by 25.4: 55 in × 25.4 = 1,397 mm. Also searched as inches to millimetres.
Quick facts
- 1 in = 25.4 mm
- 1 mm = 0.0393701 in
- Formula: mm = in × 25.4
- Quick estimate: multiply by about 25
How to convert inches to millimeters
- Take the value in inches.
- Multiply it by 25.4 (the number of millimeters in one inch).
- Round the result to the precision you need.
Worked example (a 55-inch TV screen): 55 in × 25.4 = 1397 mm.
To convert millimeters back to inches, multiply by 0.0393701, or divide by 25.4.
Source: NIST Special Publication 811 (2008), Appendix B; the international yard and pound agreement of 1959 (1 inch = 25.4 mm exactly).
Inches to Millimeters conversion table
| Inches [in] | Millimeters [mm] |
|---|---|
| 0.01 in | 0.254 mm |
| 0.1 in | 2.54 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 20 in | 508 mm |
| 50 in | 1270 mm |
| 100 in | 2540 mm |
| 1000 in | 25400 mm |
in to mm chart from 1 to 100
- 1 in 25.4 mm
- 2 in 50.8 mm
- 3 in 76.2 mm
- 4 in 101.6 mm
- 5 in 127 mm
- 6 in 152.4 mm
- 7 in 177.8 mm
- 8 in 203.2 mm
- 9 in 228.6 mm
- 10 in 254 mm
- 11 in 279.4 mm
- 12 in 304.8 mm
- 13 in 330.2 mm
- 14 in 355.6 mm
- 15 in 381 mm
- 16 in 406.4 mm
- 17 in 431.8 mm
- 18 in 457.2 mm
- 19 in 482.6 mm
- 20 in 508 mm
- 25 in 635 mm
- 30 in 762 mm
- 35 in 889 mm
- 40 in 1016 mm
- 45 in 1143 mm
- 50 in 1270 mm
- 55 in 1397 mm
- 60 in 1524 mm
- 65 in 1651 mm
- 70 in 1778 mm
- 75 in 1905 mm
- 80 in 2032 mm
- 85 in 2159 mm
- 90 in 2286 mm
- 95 in 2413 mm
- 100 in 2540 mm
Millimeters to Inches conversion table
| Millimeters [mm] | Inches [in] |
|---|---|
| 0.01 mm | 0.0003937008 in |
| 0.1 mm | 0.0039370079 in |
| 1 mm | 0.0393700787 in |
| 2 mm | 0.0787401575 in |
| 3 mm | 0.1181102362 in |
| 5 mm | 0.1968503937 in |
| 10 mm | 0.3937007874 in |
| 20 mm | 0.7874015748 in |
| 50 mm | 1.968503937 in |
| 100 mm | 3.937007874 in |
| 1000 mm | 39.3700787402 in |
Inches vs Millimeters
| Inch | Millimeter | |
|---|---|---|
| Symbol | in | mm |
| Equals | 1 in = 25.4 mm | 1 mm = 0.0393701 in |
What is an inch?
A US customary and imperial unit equal to exactly 25.4 millimeters, with 12 inches to a foot. Used in the US for screen sizes, paper, tools, and rainfall, and in the UK for height.
What is a millimeter?
One thousandth of a meter, the SI base unit of length. Used for small, precise measurements in engineering, printing, and manufacturing tolerances.
Frequently asked questions
How many millimeters are in an inch?
There are 25.4 millimeters in 1 inch (1 in = 25.4 mm).
How many inches are in a millimeter?
There are 0.0393701 inches in 1 millimeter (1 mm = 0.0393700787 in).
How do I convert inches to millimeters?
Multiply the number of inches by 25.4. For example, 10 in × 25.4 = 254 mm. To convert back, multiply by 0.0393701.
What is 10 in in millimeters?
10 in = 254 mm.
What is 100 in in millimeters?
100 in = 2,540 mm.
Is the conversion exact?
Yes. The factor comes from the official definitions of both units (NIST Special Publication 811 (2008), Appendix B; the international yard and pound agreement of 1959 (1 inch = 25.4 mm exactly)). Results are shown to up to 10 decimal places; round them to suit your purpose.
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