Convert MM to Inches Formula – Examples, FAQs, How to Convert

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What Is the mm to Inches Formula?

The mm to inches conversion formula is based on the fact that there are 25.4 millimeters in an inch. Simply divide the number of millimeters by 25.4 to get the equivalent length in inches.

The formula to convert mm to inches (millimeters to inches) is given by:

Inches = Millimeters 25.4

Understanding this conversion is critical if you work with measures in the metric system and need to present those measurements in the imperial system. The conversion formula for mm to inches is critical in this procedure, providing accurate and effortless conversions between the two. 

What is millimeter?

A millimeter (mm) is a unit of length in the metric system, which is commonly used for measuring small distances. It is equal to one-thousandth of a meter, making it a very small unit of measurement.

What is inch?

An inch (in) is a unit of length commonly used in the United States and a few other countries that do not primarily use the metric system. It is equal to 1/12th of a foot or approximately 2.54 centimeters. The inch is used for measuring shorter lengths, such as the height of a person, the width of a book, or the size of a screen. It is a larger unit than the millimeter and is often found in everyday applications, especially in the United States, for measuring various objects and distances.

Observe the given ruler. It shows measurements in inches at the top and mm at the bottom. The smallest division at the bottom represents 1 mm. Notice that the 1 inch mark roughly lines up with the 25.4 mm mark.

1 mm and 1 in on a ruler

Formula to Convert mm to Inches

The millimeter to inches conversion formula depends on the following equations:

  • 1 mm = 0.0393701 inches
  • 1 inch = 25.4 mm

1 mm=125.4 inches = 0.03937 inches

The formula to convert millimeters (mm) to inches is

Inches =mm25.4

N millimeters=N × 0.03937 inches

How to Convert Millimeters into Inches

We can easily convert measurements in mm to inches by-

  • Note down the given length in millimeters.
  • Divide the length in millimeters by 25.4.

OR

Multiply the length in millimeters by 0.03937.

  • Write the resulting value in inches.

Example: If you have 100 millimeters, you can calculate it as:

Inches = 100 mm 25.4 = 3.93700787 inches (approximately 3.94 inches when rounded to two decimal places).

The mm to Inches Conversion Table

Here is a conversion table to instantly convert mm to Inches. These values in the table are rounded to four decimal places. You may use the formula to convert mm to inches for more precise measurements.

Millimeters (mm)Inches (approximate)
1 mm0.0394 inches
5 mm0.1969 inches
10 mm0.3937 inches
15 mm0.5906 inches
20 mm0.7874 inches
25 mm0.9843 inches
30 mm1.1811 inches
35 mm1.3780 inches
40 mm1.5748 inches
45 mm1.7717 inches
50 mm1.9685 inches
100 mm3.9370 inches
150 mm5.9055 inches
200 mm7.8740 inches
250 mm9.8425 inches
300 mm11.8110 inches

Facts about the mm to Inches Conversion Formula

  • The conversion factor for the mm to inches conversion is 25.4.
  • The millimeter is a smaller unit of measurement than the inch, with approximately 0.0394 inches in one millimeter.

Conclusion

In this article, we learned about the conversion from millimeters to inches, an important measurement skill for everyday measurements. The mm to inches conversion requires simple calculations. You just have to know the conversion factor or you can even use the conversion table provided above for a quick check. Let’s solve a few examples and practice multiple-choice questions (MCQs) for better comprehension.

Solved Examples on the mm to Inches Conversion Formula

Example 1: Convert 50 mm into inches.

Solution:

Let’s use the mm to inches conversion formula.

Length in inches = Length in mm ÷ 25.4

Length in inches  ≈ 1.9685 inches (rounded to four decimal places)

Example 2: Compare 75 millimeters to 3 inches.

Solution:

To compare these two measurements, they must be in the same unit.

Let us convert 75 millimeters into inches.

Inches = 75 mm x 0.03937 ≈ 2.9528 inches (rounded to four decimal places)

Thus, 75 mm ≈ 2.9528 inches

2.9528 inches < 3 inches

Thus, 75 mm < 3 inches

Example 3: What is 120 millimeters in inches?

Solution:

120 mm =120 x 0.03937 inches

120 mm ≈ 4.72 inches (rounded to two decimal places)

Therefore, the measurement in inches is approximately 4.72 inches.

Example 4: Convert 150 mm to inches.

Solution:

Inches $= \frac{mm}{25.4}$

Inches $= \frac{150\; mm}{25.4}$

150 mm = 5.9055 inches

Example 5: What will be 300 millimeters in inches?

Solution:

Inches $ = \frac{mm}{25.4}$

Inches $= \frac{300\; mm}{25.4}$

300 mm = 11.8110 inches

Practice Problems on the mm to Inches Conversion Formula

Convert MM to Inches Formula - Examples, FAQs, How to Convert

Attend this quiz & Test your knowledge.

1

Which one is the correct formula to convert millimeters (mm) to inches?

Inches $= \frac{mm}{25.4}$
Inches = mm x 25.4
Inches = mm + 25.4
Inches = mm - 25.4
CorrectIncorrect
Correct answer is: Inches $= \frac{mm}{25.4}$
Since one inch is equal to 25.4 mm, the correct formula used to convert millimeters to inches is shown in option (a).
2

What will be 10 mm in inches?

0.3937 inches
0.0394 inches
1.5748 inches
0.7874 inches
CorrectIncorrect
Correct answer is: 0.3937 inches
Inches $= \frac{10\; mm}{25.4}$
10 mm ≈ 0.3937 inches (rounded to four decimal places)
3

How many millimeters are there in 1 inch?

10 mm
25.4 mm
100 mm
50 mm
CorrectIncorrect
Correct answer is: 25.4 mm
1 in = 25.4 mm
4

To convert millimeters to inches, you

add 0.0394
divide by 0.0394
multiply by 25.4
divide by 25.4
CorrectIncorrect
Correct answer is: divide by 25.4
To convert millimeters to inches, you divide by 25.4.

Frequently Asked Questions about the mm to Inches Conversion Formula

There are 25.4 millimeters in an inch. For a quick conversion and estimation, we can divide the length in millimeters by 25. For example, 100 mm is approximately equal to $100 \div 25 = 4$ inches.

One millimeter is approximately equal to 0.0394 inches. There are 25.4 millimeters in an inch.

To convert millimeters into inches, divide the length in millimeters by 25.4.

One millimeter (mm) equals roughly 0.03937 inches. To be more specific, one millimeter is 0.03937007874 inches. This means that there are approximately 0.03937 inches for every millimeter.