Millimeters To Inches Converter

Convert millimeters to inches fast with the exact formula, quick examples, and a simple reference table.

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Table of Contents

Convert Millimeters to Inches

Millimeters and inches both measure length, but they are used in different places.

This conversion helps when reading tool sizes, product dimensions, and technical drawings.

Quick Answer

1 Millimeter = 0.0393700787 Inches

Example 1: 10 millimeters = 0.393700787 inches

Example 2: 50 millimeters = 1.968503937 inches

Conversion Formula

inches = millimeters ÷ 25.4

This means you divide the millimeter value by 25.4 to get the same length in inches.

Write down your value in millimeters.
Divide it by 25.4.
The result is the value in inches.

What Is Millimeter

A millimeter is a very small metric unit of length, equal to one thousandth of a meter.

Measuring thickness of paper, plastic, and metal sheets
Small parts like screws, bolts, and drill bits
Engineering drawings and manufacturing tolerances
Rainfall measurements in weather reports
Jewelry and watch part sizes

What Is Inches?

An inch is an imperial and US customary unit of length, commonly used in the United States.

Screen sizes like TVs, monitors, and phones
Tool and hardware sizing in many US products
Furniture and room measurements
Pipe and plumbing sizes
Height and distance in everyday US use

Real Life Examples

Here are common situations where you might need to convert millimeters to inches.

A 6 mm screw is about 0.2362 inches in diameter.
A phone that is 8 mm thick is about 0.3150 inches thick.
A 12 mm drill bit is about 0.4724 inches.
A 2 mm washer thickness is about 0.0787 inches.
A 25.4 mm measurement is exactly 1 inch.
A 100 mm ruler mark is about 3.9370 inches.
A bike part listed as 31.8 mm is about 1.2520 inches.
A 3 mm gap is about 0.1181 inches.

Quick Tips

Remember the key fact, 25.4 mm = 1 inch.
For a quick estimate, divide mm by 25.
To go the other way, multiply inches by 25.4.
For shopping and DIY, rounding to 2 or 3 decimals is usually enough.
For engineering, keep more decimals to avoid small errors.
If your result looks too big, check that you divided by 25.4, not multiplied.

Table Overview

Millimeters	Inches
1 mm	0.03937 in
2 mm	0.07874 in
3 mm	0.11811 in
4 mm	0.15748 in
5 mm	0.19685 in
6 mm	0.23622 in
7 mm	0.27559 in
8 mm	0.31496 in
9 mm	0.35433 in
10 mm	0.39370 in
11 mm	0.43307 in
12 mm	0.47244 in
13 mm	0.51181 in
14 mm	0.55118 in
15 mm	0.59055 in

FAQs

How do you convert mm to inches?

Divide the millimeter value by 25.4. The result is inches.

Why is 25.4 used in the formula?

Because 1 inch is defined as exactly 25.4 millimeters.

What is 10 mm in inches?

10 mm = 10 ÷ 25.4 = 0.3937 inches (rounded).

What is 100 mm in inches?

100 mm = 3.9370 inches (rounded to 4 decimals).

How many inches are in 1 mm?

1 mm is about 0.03937 inches.

Should I round the result?

For most everyday uses, rounding to 2 or 3 decimals is fine. For precise work, keep more decimals.

How do I convert inches back to mm?

Multiply inches by 25.4 to get millimeters.