Millimeter to Inch Converter
Length · unit-converter
Convert Millimeter to Inch with a fixed input and output unit, step-by-step formula line, and reference tables. All calculations use SI-based definitions (international yard, nautical mile, etc.).
Calculator
From: Millimeter (mm)
To: Inch (in)
About Millimeter
The millimeter is a metric unit equal to one thousandth of a meter (0.001 m). It is used for precision engineering, 3D printing, and small tolerances.
About Inch
The inch is an imperial and US customary unit equal to exactly 0.0254 meters. Twelve inches equal one feet; it is used for screen sizes, tools, and fine measurements.
How to convert millimeters to inches
1 millimeter is equal to 0.03937007874016 inch:
1 mm = (0.001 m ÷ 0.0254 m) in = 0.03937007874016 in
Each millimeter is defined as 0.001 m and each inch as 0.0254 m, so one mm equals 0.001 ÷ 0.0254 in = 0.03937007874016 in.
Let d(mm) be the numeric value of the same length measured in Millimeter (mm), and d(in) the value in Inch (in). Then:
d(in) = d(mm) × (0.001 / 0.0254)
Equivalently, divide by how many mm fit into one in (meters per in divided by meters per mm):
d(in) = d(mm) ÷ 25.4
Or: inch = millimeter ÷ 25.4
Examples
Example #1: Convert 20 mm to inch
20 mm = 20 mm × (0.001/0.0254) in = 0.7874015748 in
20 mm = 20 mm ÷ 25.4 = 0.7874015748 in
Example #2: Convert 50 mm to inch
50 mm = 50 mm × (0.001/0.0254) in = 1.968503937 in
50 mm = 50 mm ÷ 25.4 = 1.968503937 in
Summary
To convert Millimeter to Inch, multiply the value in mm by the ratio of meters per mm divided by meters per in. Equivalently: value_in = value_mm × (0.001 / 0.0254). Numerically, 1 mm equals 0.03937007874015748 in.
Relationship context
You are converting between metric (SI) (Millimeters) and US customary / imperial (Inches). Metric units are decimal; imperial units use inches, feet, yards, and miles tied to the international yard definition. Nautical miles are defined in meters (1 nmi = 1,852 m). This tool uses SI-based factors so results stay consistent with modern standards.
Conversion tables
| Millimeter (mm) | Inch (in) |
|---|---|
| 0.1 | 0.0039370079 |
| 1 | 0.0393700787 |
| 2 | 0.0787401575 |
| 3 | 0.1181102362 |
| 4 | 0.157480315 |
| 5 | 0.1968503937 |
| 6 | 0.2362204724 |
| 7 | 0.2755905512 |
| 8 | 0.3149606299 |
| 9 | 0.3543307087 |
| Millimeter (mm) | Inch (in) |
|---|---|
| 10 | 0.3937007874 |
| 20 | 0.7874015748 |
| 30 | 1.1811023622 |
| 40 | 1.5748031496 |
| 50 | 1.968503937 |
| 60 | 2.3622047244 |
| 70 | 2.7559055118 |
| 80 | 3.1496062992 |
| 90 | 3.5433070866 |
| 100 | 3.937007874 |
Conversions outside the hub list
The grid on the category page lists hub units only. These pairs include at least one unit outside that hub set (same tools: formulas and tables on each page).
- mm to nmiMillimeter to Nautical Mile
- mm to chainMillimeter to Chain
- mm to fathomMillimeter to Fathom
- mm to umMillimeter to Micrometer
- mm to nmMillimeter to Nanometer
- mm to angstromMillimeter to Angstrom
- mm to pmMillimeter to Picometer
- nmi to inchNautical Mile to Inch
- chain to inchChain to Inch
- fathom to inchFathom to Inch
- um to inchMicrometer to Inch
- nm to inchNanometer to Inch