Inches to Millimeters Converter
Quick answer: To convert inches to millimeters, multiply by 25.4. For example, 10 in is 254 mm. One inch equals 25.4 mm.
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Use the Inches to Millimeters Converter
Inches to Millimeters formula and what each symbol means
mm = in × 25.4
| Symbol | Meaning |
|---|---|
| in | Inch |
| mm | Millimeter |
Inches to Millimeters examples
1 in
1 in × 25.4 = 25.4 mm.
10 in
10 in × 25.4 = 254 mm.
100 in
100 in × 25.4 = 2,540 mm.
Inches compared with Millimeters
One in is 25.4 times as large as one mm, so your number gets bigger when you convert inches to millimeters and smaller when you convert back. If the answer is not larger than what you typed, you divided instead of multiplying.
About inches and millimeters
Inch (in): The international inch, exactly 2.54 centimetres. Millimeter (mm): One thousandth of a metre.
How to calculate Inches to Millimeters step by step
- Enter the value in in (the starting unit).
- Multiply by 25.4, because 1 in = 25.4 mm.
- The product is the value in mm. To go back, divide by 25.4 or multiply by 0.03937008.
Popular typography conversions
How to read your Inches to Millimeters result
Quick estimate: multiply by about 25 to get millimeters from inches; this is within 1.6% of the exact factor. In CSS, one inch is exactly 96 pixels, 72 points and 6 picas.
| INCHES | MILLIMETERS |
|---|---|
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1,270 |
| 100 | 2,540 |
| 1,000 | 25,400 |
Millimeters to Inches: quick table
| MILLIMETERS | INCHES |
|---|---|
| 1 | 0.03937008 |
| 5 | 0.1968504 |
| 10 | 0.3937008 |
| 25 | 0.984252 |
| 50 | 1.968504 |
| 100 | 3.937008 |
| 250 | 9.84252 |
| 500 | 19.68504 |
Common mistakes when calculating Inches to Millimeters
- Confusing a CSS pixel with a physical screen pixel; a CSS pixel is a reference unit of 1/96 inch.
- Dividing when you should multiply: from in to mm multiply by 25.4; from mm to in divide by 25.4.
Inches to Millimeters FAQ
How many mm are in 1 in?
1 in equals 25.4 mm.
How many in are in 1 mm?
1 mm equals 0.03937008 in.
Is 1 in = 25.4 mm an exact conversion?
The factor is shown rounded to 7 significant figures (25.4). The calculator above uses more digits.
What is an inch (in)?
The international inch, exactly 2.54 centimetres.
How can I estimate inches to millimeters in my head?
Quick estimate: multiply by about 25 to get millimeters from inches; this is within 1.6% of the exact factor.
What is 200 in in millimeters?
200 in = 5,080 mm (since 200 × 25.4).
What is 3 in in millimeters?
3 in = 76.2 mm (since 3 × 25.4).
What is 30 in in millimeters?
30 in = 762 mm (since 30 × 25.4).
How many decimals should I keep when converting in to mm?
Match the precision of your original measurement. For example, 254 mm rounds to 254 mm at 3 significant figures; keep more digits only for engineering or scientific work.
More in Typography converters
- Inches to Points Converter
- Centimeters to Pixels Converter
- Millimeters to Centimeters Converter
- Centimeters to Picas Converter
- Centimeters to Millimeters Converter
- Millimeters to Picas Converter
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Method, review and disclaimer
Edited by: Hemant Kumar and Anjita Rai, founders of ToolsVault (SEO and content professional, not a licensed adviser). Method: this tool runs in your browser using the formula shown on this page; the numbers you enter are not sent to our servers. Sources: W3C CSS Values and Units: absolute lengths (1in = 96px = 72pt = 6pc)