MM to Inches Converter | Convert Millimeters to Inches Online

Unit	Value
Inches [in]

Understanding Millimeters and Inches

When dealing with precise measurements, especially in engineering, manufacturing, and crafts, two common units are the millimeter (mm) and the inch (in). These units originate from different measurement systems and serve distinct purposes globally.

What is a Millimeter (mm)?

The millimeter is a unit of length in the International System of Units (SI), which is the modern form of the metric system. It is one thousandth of a meter. The metric system is used by most countries worldwide for scientific, commercial, and general purposes due to its decimal nature and ease of conversion.

Origin: Part of the metric system, developed in France in the late 18th century.
Definition: 1 millimeter = 0.001 meters.
Common Uses: Millimeters are widely used in fields requiring high precision, such as mechanical engineering, architecture, electronics, and for measuring small objects like screws, paper thickness, or rainfall.

What is an Inch (in)?

The inch is a unit of length in the imperial system and the U.S. customary system of measurement. While the United Kingdom and Canada have officially adopted the metric system, the inch (and feet) remains widely used in the United States and in certain industries globally.

Origin: Historically, the inch was based on the width of a thumb or three barleycorns laid end-to-end.
Definition: Since 1959, the international inch has been precisely defined as 25.4 millimeters. This standardization facilitates conversions between metric and imperial systems.
Common Uses: Inches are primarily used in the United States for various measurements, including screen sizes (TVs, monitors), tire diameters, clothing sizes, and in construction and DIY projects.

Why Convert Between Millimeters and Inches?

The need to convert between millimeters and inches arises frequently in international trade, manufacturing, and design. For example, a product designed in metric (millimeters) might need to be manufactured or sold in a country that primarily uses imperial units (inches), or vice versa. Accurate conversion ensures compatibility and precision in diverse contexts.

Millimeters to Inches Conversion Table

Millimeters [mm]	Inches [in] (approx.)
1 mm	0.03937 in
5 mm	0.19685 in
10 mm	0.393701 in
25 mm	0.984252 in
50 mm	1.968504 in
100 mm	3.937008 in
254 mm	10 in
500 mm	19.685039 in
1000 mm	39.370079 in

How to Convert Millimeters to Inches

Converting a measurement from millimeters (mm) to inches (in) is a straightforward process. The fundamental conversion factor to remember is based on the international definition of the inch:

1 inch is exactly equal to 25.4 millimeters.

Therefore, to convert a value from millimeters to inches, you simply divide your millimeter value by 25.4.

Here's the simple formula:
Inches = Millimeters / 25.4

Let's look at an example:
Suppose you have a measurement of 100 millimeters and you want to know what that is in inches.
Using the formula:
100 mm / 25.4 = 3.937007874 inches
So, 100 millimeters is approximately equal to 3.94 inches.

If you need to convert from inches back to millimeters, you would multiply your inch value by 25.4.