How to Convert Millimeters to Inches

Step-by-Step Guide

1. 1

   Step 1: Learn the conversion factor.

   One inch is the same length as
   25.4 millimeters.
   
   You can write this "conversion factor" as a fraction: 1inch25.4mm{\displaystyle {\frac {1inch}{25.4mm}}}.
   
   Any two units have a special conversion factor for converting between them.
   
   If you don't know what it is, you can look it up online or in a textbook.
2. 2

   Step 2: Understand the conversion factor.

   The top and bottom of the fraction are the same length, just written in different units.
   
   This means the fraction is equal to 1, just like the fractions 33{\displaystyle {\frac {3}{3}}} or 88{\displaystyle {\frac {8}{8}}} simplify to
   1.
   
   Remember, multiplying a number by 1 doesn't change its value.
   
   That means you can multiply your measurement by this factor and the length will be the same.
   
   The only difference is the units: your answer will be written in inches instead of millimeters. , Make sure to write down all units in your measurement.
   
   For example, here's what you would write down to convert 16 millimeters (mm) into inches (in): 16 mm x 1in25.4mm{\displaystyle {\frac {1in}{25.4mm}}} = ? , If the same unit appears on the top and bottom of a fraction, they cancel out.
   
   If you've set up your problem correctly, the millimeters will cancel out and you'll be left with just inches. 16 mm x 1in25.4mm{\displaystyle {\frac {1in}{25.4mm}}} = ? Cancel out the millimeters:16 x 1in25.4{\displaystyle {\frac {1in}{25.4}}} = ? Since the only unit left is inches, your answer will be in inches. , Finish the math problem by hand or on a calculator. 16 x 1in25.4{\displaystyle {\frac {1in}{25.4}}} = 16 in ÷
   25.4 = about
   0.63 inches
3. 3

   Step 3: Write down the multiplication problem.

4. 4

   Step 4: Cancel out the units.

5. 5

   Step 5: Solve the problem.

Detailed Guide

About the Author