Inches to Millimeters converter (in to mm)
Convert Inches (in) to Millimeters (mm) with this free calculator. Type a value, press Convert, and the page applies the same factor shown in the formula below — no rounded shortcut, and nothing is stored on a server.
How to convert Inches to Millimeters
1 inch (in) is equal to 25.4 millimeters (mm).
1 in = 25.4 mm
The length L in millimeters (mm) is equal to the length L in inches (in) multiplied by 25.4:
Example: Convert 5 in to mm:
L(mm) = 5 × 25.4 = 127 mm
What is a Inches?
The inch (in) is 1÷12 of a foot, defined as exactly 25.4 millimetres. Screens, lumber, and US height measurements use inches.
What is a Millimeters?
The millimetre (mm) is 1÷1,000 of a metre. Machining, rainfall, and small product dimensions are specified in millimetres.
This page converts length from Inches into Millimeters. One in equals 25.4 mm.
Inches to Millimeters conversion table
Common in values and the matching mm result, calculated with the same factor as the widget. Highlight a nearby row if you want a quick check without entering a number.
| Inches (in) | Millimeters (mm) |
|---|---|
| 0 in | 0 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 6 in | 152.4 mm |
| 12 in | 304.8 mm |
| 18 in | 457.2 mm |
| 24 in | 609.6 mm |
| 30 in | 762 mm |
| 36 in | 914.4 mm |
| 42 in | 1066.8 mm |
| 48 in | 1219.2 mm |
| 54 in | 1371.6 mm |
| 60 in | 1524 mm |
| 72 in | 1828.8 mm |
| 84 in | 2133.6 mm |
| 96 in | 2438.4 mm |
| 108 in | 2743.2 mm |
| 120 in | 3048 mm |
How this calculator works
The form on this page is a Inches-to-Millimeters converter. After you enter a number, JavaScript multiplies or rearranges it with the published conversion factor and writes the mm result in the output box. The step-by-step panel repeats the arithmetic so you can copy it into homework or a spreadsheet.
Reviewed by Hamsen, founder of GigaTables and a biology engineer. See the about page for how formulas are checked before a tool is published.
FAQ
How many mm are in 1 in?
1 in = 25.4 mm.
How do I convert Inches to Millimeters?
The length L in millimeters (mm) is equal to the length L in inches (in) multiplied by 25.4:
Is this in to mm converter free?
Yes. GigaTables calculators are free to use in a browser. You do not need an account, and the values you type are not uploaded.