Inch to Millimeter (in to mm) Conversion Calculator


What Is Inch (In)?

An inch (symbol: in) is a unit of length in the imperial and US customary systems of measurement. An inch was defined to be equivalent to exactly 25.4 millimeters in 1959. There are 12 inches in a foot and 36 inches in a yard.The term “inch” was derived from the Latin unit “uncia” which equated to “one-twelfth” of a Roman foot.

Inches can also be denoted using the ″ symbol, otherwise known as a double-prime. Often a double-quote (“) is used instead of a double-prime for convenience. A double-prime is commonly used to express 1 in as 1″.

What Is Millimeter (mm)?

The millimeter (mm) is a length unit utilized in the metric system to quantify minute distances or dimensions. Denoting one thousandth of a meter in value, it functions as a metric unit in accordance with the meter, which serves as the foundational length unit in the International System of Units (SI).

In simpler terms, there are 1,000 millimeters in one meter. Millimeters are commonly used for precise measurements in various fields such as engineering, manufacturing, construction, science, and everyday tasks where accuracy in smaller measurements is required.

This unit of measurement is widely used in engineering-related drawings and specifications. Hence, while most standard rulers have 1 mm graduations, the ones specifically used for engineering purposes also have 0.5 mm graduations.

Common usage:

  • Used to measure the size of the dial of a wristwatch
  • used to measure the size of a diamond
  • Used to measure the size of a coin

How to Convert Inches (In) to Millimeter (mm)?

Converting inches to millimeters is a straightforward process that involves multiplying the given measurement by a conversion factor. The conversion factor for inches to millimeters is 25.4, as there are 25.4 millimeters in one inch. To convert inches to millimeters, simply multiply the number of inches by 25.4.

It is important to note that this conversion factor is constant and can be used for any measurement in inches. Whether you are converting a small or large measurement, the process remains the same. By multiplying the number of inches by 25.4, you can easily convert inches to millimeters and accurately compare measurements in these two units.


1) Convert 500 inches to millimeters.

Solution 1:

Step 1: The given inch is 500.
Step 2: To convert 500 inches to millimeters, substitute the given values at the required places in the formula. Hence,
X in = X × 25.4 mm
500 in = 25.4 ×500 mm
= 12700 mm
Therefore, 500 inches is 12700 millimeters.

2) Convert 15 inches to millimeters.

Solution 2 :

Step 1: The given inches is 15.
Step 2: To convert 15 inches to millimeters, substitute the values at the required places in the formula. Hence,

X in = X × 25.4 mm
15 in = 15 × 25.4 mm
= 381 mm
Therefore, 15 inches is 381 mm.

Inches (In) to Millimeter (mm) Conversion Formula:

The conversion from inches to millimeters is a simple process devoid of any challenging steps. The following equation will serve as the foundational reference when converting one inch to millimeters.

1 inch is equal to 25.4 millimeters:

1″ = 25.4 mm

Hence, the Inch unit is converted into an equivalent millimeter.

We learned to convert inches to millimeters, which is quite useful! This transformation has several uses.

Inch (In) To Millimetre (Mm) Conversion Table

Take a look at the chart that is provided below if you are interested in learning more about how to convert feet to meters.

Inch (in)Millimeter (mm)Conversion of  Inch to Millimetre (in to mm)
1 in25.4 mm1 in is 25.4 mm
2 in50.8 mm2 in is 50.8 mm
3 in76.2 mm3 in is 76.2 mm
4 in101.6 mm4 in is 101.6 mm
5 in127 mm5 in is 127 mm
6 in152.4 mm6 in is 152.4 mm
7 in177.8 mm7 in is 177.8 mm
8 in203.2 mm8 in is 203.2 mm
9 in228.6 mm9 in is 228.6 mm
10 in254 mm10 in is 254 mm
20 in508 mm20 in is 508 mm
30 in762 mm30 in is 762 mm
50 in1270 mm50 in is 1270 mm
100 in2540 mm100 in is 2540 mm
200 in5080 mm200 in is 5080 mm
300 in7620 mm300 in is 7620 mm
400 in10160 mm400 in is 10160 mm
500 in12700 mm500 in is 12700 mm
600 in15240 mm600 in is 15240 mm
700 in17780 mm700 in is 17780 mm
800 in20320 mm800 in is 20320 mm
900 in22860 mm900 in is 22860 mm
1000 in25400 mm1000 in is 25400 mm


Concerning the conversion from Inch (In) To Millimetre (Mm), there is no need to be concerned. You are able to convert Inch to millimeters and vice versa with relative ease by using a formula or resources found on the internet. Check your results and make sure you are using conversion calculators or sources that are accurate.

Making use of a reliable “in to mm calculator” will allow you to save time while also ensuring accuracy. The instantaneous and accurate conversion of data is made possible by these technologies, which simplify procedures. Once you have learned how to convert inch to millimeters, you will be able to simplify measurement conversions in your everyday life! 

Frequently Asked Questions (FAQs) on Inch (In) To Millimetre (Mm) Calculator

1) How do you convert inches to mm?

Answer: To convert the inch to the millimeter, multiply the required inches by 25.4 as

1 in = 25.4 mm.


Y in = Y × 25.4

2) What is 1 inch equal to in mm?

Answer: 1 in = 25.4 mm

3) How to convert 25 in to mm?

Answer: To convert the inch to the millimeter, multiply the required inches by 25.4 as

1 in = 25.4 mm.


Y in = Y × 25.4

Hence 25 in is,

25 in = 25 × 25.4 mm

= 635 mm

Therefore, 25 inches is 635 mm.

4) How many Millimeters in an Inch?

Answer: There are 25.4 millimeters in an inch, i.e. 1 inch (in) = 25.4 millimeter (mm).

5) How many mm is 1 ⁄ 4 Inch?

Answer: 1/4 in is equal to 6.35 mm.

6) How many Mm in 100 Inches?

Answer: 100 in = 2539.999961853 mm.

Read also: Meter to Millimeter Conversion | Meter to Yard Conversion | Meter to Centimeters Conversion

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