Convert Millimeters to Inches

Instantly convert millimeters (mm) to inches (in). Enter a value to see the result and the conversion formula.

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Quickly convert units of weight, volume, length, temperature, area, data, speed and time. Results update instantly as you type.

How the unit converter works

Each category uses a base (reference) unit. For example: meters (m) for length, kilograms (kg) for weight, liters (L) for volume, seconds (s) for time, and so on. Your value is first converted to the base unit, then to the target unit - a simple method that reduces rounding errors.

A brief history of units

The metric system was created in the late 18th century to standardize measurements (meter, kilogram, liter). In contrast, units such as the inch, yard, or mile come from older traditions and were standardized later. Today, we often switch between systems - which is why a clear and reliable unit converter is so useful.

About this conversion

The conversion between millimeter and inch reflects the coexistence of multiple measurement systems. Standardized conversion factors make it easier to interpret values across contexts, for education, trade, and engineering.

When to use this conversion

Use this when values are expressed in millimeter but your context requires inch, in everyday life, education, travel, and professional settings.

Formula

1 mm = 0.0393701 in

  • 1 mm = 0.0394 in
  • 10 mm = 0.3937 in
  • 100 mm = 3.937 in

Tip: You can swap units and convert decimals. Results are rounded for readability.

FAQ

How do I convert millimeters (mm) to inches (in)?

Enter a value in mm. This page applies the conversion formula and shows the equivalent value in in.

Can I convert decimal values?

Yes. Decimals are supported, and the result is rounded for readability.

Is the result accurate?

Yes. Conversions use standard factors. Minor rounding may appear in the displayed result.