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Co-authored byDavid Jia
Last Updated: May 26, 2023
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The U.S. uses the imperial measurement system which includes inches, but much of the rest of the world uses the metric system.[1] Sometimes, you’ll need to convert a measurement from inches to millimeters for better understanding. Converting is simple when you know the proper equation!
Convert Inches to Millimeters
Use this conversion calculator to convert inches to millimeters.
LENGTH
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Formula
Part 1
Part 1 of 4:
Basic Equation
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1
Understand the relationship between inches and millimeters. One inch is internationally accepted as being equivalent to 25.4 millimeters.[2]
- Written as an equation, this relationship is represented as: 1 in = 25.4 mm
- This official, standardized measurement has been set on international records since 1959.
- Both inches and millimeters are units of measurement. Inches belong to the English system of measurement, while millimeters belong to the metric system of measurement.
- While inches are used in the United States, you will often need to convert this unit of measurement to one belonging to the metric system (like millimeters) for scientific purposes.
- Conversely, there are 0.0393700787402 inches in one millimeter.[3]
2
Write down the inches measurement. To convert a measurement taken in inches, you need to begin the problem by writing down the original measurement.
- This measurement will then be converted into millimeters by comparing it to the relationship between inches and millimeters.
- Example: 7 inches
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3
Multiply this measurement by 25.4. You need to multiply the current inches measurement by the ratio of millimeters to inches, or 25.4 mm / 1 in.
- The inches value in this ratio needs to be placed in the denominator since it will have to cancel out the inches value in your original measurement. Once all the inches are canceled out, the millimeters will be the only remaining unit of measurement.
- Example: 7 in * (25.4 mm / 1 in) = 177.8 mm * (in/in) = 177.8 mm
4
Write down the final answer. If you did the problem correctly, the answer you come up with should be your final answer in millimeters.
- Example: 177.8 mm
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Part 2
Part 2 of 4:
Shortcuts
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1
Check a ruler. One ruler is 12 inches long or 1 foot. Many rulers list the inches on one side but also list centimeters and millimeters on the other side. If your original measurement is 12 inches or below, you can use one of these rulers to measure the same distance in millimeters.
- Note that the millimeter marks on a ruler are all the small dashes in between the larger centimeter measurements. There should be 10 mm per 1 cm.
2
Use a website to automatically convert the measurement. If you need to quickly find out the millimeter equivalent to a measurement in inches, you can do so by using an automatic conversions website.
- Go to the website and locate the conversion boxes.
- Type the numbers into their respective boxes and select the units you are trying to convert, if necessary.
- Hit the “Calculate” button or other corresponding button to be shown the answer.
- Websites that will calculate this conversion for you include:
- MetricConversions.Org (http://www.metric-conversions.org/length/inches-to-millimeters.htm)
- CheckYourMath.Com (http://www.checkyourmath.com/convert/length/inches_mm.php)
- Additionally, you can type the problem (i.e., 7 in = mm) directly into most major search engines, including Google and Bing, and the search engine should be able to convert the problem and return the answer to you on the results page.
3
Look at a common conversions chart. For smaller amounts of inches, you might be able to locate the measurement on a conversion chart, such as the one below. Locate the number of inches and look beside it to view the number of millimeters equal to the inches value.
- 1/64 in = 0.3969 mm
- 1/32 in = 0.7938 mm
- 1/16 in = 1.5875 mm
- 1/8 in = 3.1750 mm
- 1/4 in = 6.3500 mm
- 1/2 in = 12.7000 mm
- 3/4 in = 19.0500 mm
- 7/8 in = 22.2250 mm
- 15/16 in = 23.8125 mm
- 31/32 in = 24.6062 mm
- 63/64 in = 25.0031 mm
- 1 in = 25.4001 mm
- 1 1/8 in = 28.5750 mm
- 1 1/4 in = 31.7500 mm
- 1 3/8 in = 34.9250 mm
- 1 1/2 in = 38.1000 mm
- 1 5/8 in = 41.2750 mm
- 1 3/4 in = 44.4500 mm
- 2 in = 50.8000 mm
- 2 1/4 in = 57.1500 mm
- 2 1/2 in = 63.5000 mm
- 2 3/4 in = 69.8500 mm
- 3 in = 76.2000 mm
- 3 1/4 in = 82.5500 mm
- 3 1/2 in = 88.9000 mm
- 3 3/4 in = 95.2500 mm
- 4 in = 101.6000 mm
- 4 1/2 in = 114.3000 mm
- 5 = 127.0000 mm
- 5 1/2 in = 139.7000 mm
- 6 in = 152.4000 mm
- 8 in = 203.2000 mm
- 10 in = 254.0000 mm
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Part 3
Part 3 of 4:
Related Tasks
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1
Convert inches to centimeters. There are 2.54 cm in 1 inch, so in order to convert inches to centimeters, you need to multiply the original inches measurement by a value of 2.54 centimeters.[4]
- Example: 7 in * (2.54 cm / 1 in) = 17.78 cm
- Note that the number of centimeters will be one decimal place larger than the number of millimeters. If you have the number of millimeters, you can also find the number of centimeters by shifting the decimal place one numeral over to the left.
2
Convert inches to meters. There are 0.0254 m in 1 inch, so in order to convert inches to meters, you need to multiply the original inches measurement by a value of 0.0254 m.
- Example: 7 in * (0.0254 m / 1 in) = 0.1778 m
- Note that the number of meters will be three decimal places larger than the number of millimeters. If you have the number of millimeters, you can also find the number of meters by shifting the decimals place three numerals over to the left.
3
Convert millimeters to inches. If you want to calculate the number of inches when you have the number of millimeters, you can do so by either multiplying the number of millimeters by 0.0393700787 inches or by dividing the number of millimeters by 25.4 millimeters.
- Example: 177.8 mm * (0.0393700787 in / 1 mm) = 7 in
- Example: 177.8 mm * (1 in / 25.4 mm) = 7 in
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Part 4
Part 4 of 4:
Examples
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1
Answer the question: how many millimeters is 4.78 inches? To find the answer, you will need to multiply 4.78 inches by 25.4 millimeters.
- 4.78 in * (25.4 mm / 1 in) = 121.412 mm
2
Convert 117 inches into millimeters. Do so by multiplying 117 inches by 25.4 millimeters.
- 177 in * (25.4 mm / 1 in) = 4495.8 mm
3
Determine how many millimeters are in 93.6 inches. This answer can be found by multiplying 93.6 inches and 25.4 millimeters.
- 93.6 in * (25.4 mm / 1 in) = 2377.44 mm
4
Figure out how to convert 15.101 inches into millimeters. Find the answer by multiplying 15.101 inches and 25.4 millimeters.
- 15.101 * (25.4 mm / 1 in) = 383.5654 mm
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Calculator, Practice Problems, and Answers
Sample Converting Inches to Millimeters Calculator
Sample Converting Inches to Millimeters Practice Problems
Sample Converting Inches to Millimeters Practice Answers
Community Q&A
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Question
How do I convert 1/16" to mm? I need to show my work, but I am not sure how to set the problem up.
Donagan
Top Answerer
One inch equals 25.4 millimeters. Therefore, 1/16 of an inch equals 25.4 / 16 millimeters (roughly 1½ mm).
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Question
How do I convert centimeters to millimeters?
Donagan
Top Answerer
Multiply the number of centimeters by 10.
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Question
Can you show me the problem of 3/32 inches converted to millimeters?
Donagan
Top Answerer
Multiply 25.4 by 3, then divide by 32.
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References
- ↑ https://www.interexchange.org/articles/career-training-usa/2012/05/24/imperial-vs-metric-system/
- ↑ https://www.interexchange.org/articles/career-training-usa/2012/05/24/imperial-vs-metric-system/
- ↑ http://www.convertunits.com/from/inches/to/mm
- ↑ https://www.mathsisfun.com/measure/us-standard-length.html
About This Article
![How to Convert Inches to Millimeters: 14 Steps (with Pictures) (41) How to Convert Inches to Millimeters: 14 Steps (with Pictures) (41)](https://i0.wp.com/www.wikihow.com/images/thumb/c/c6/David_Jia.png/-crop-100-100-100px-David_Jia.png)
Co-authored by:
David Jia
Math Tutor
This article was co-authored by David Jia. David Jia is an Academic Tutor and the Founder of LA Math Tutoring, a private tutoring company based in Los Angeles, California. With over 10 years of teaching experience, David works with students of all ages and grades in various subjects, as well as college admissions counseling and test preparation for the SAT, ACT, ISEE, and more. After attaining a perfect 800 math score and a 690 English score on the SAT, David was awarded the Dickinson Scholarship from the University of Miami, where he graduated with a Bachelor’s degree in Business Administration. Additionally, David has worked as an instructor for online videos for textbook companies such as Larson Texts, Big Ideas Learning, and Big Ideas Math. This article has been viewed 369,747 times.
21 votes - 76%
Co-authors: 17
Updated: May 26, 2023
Views:369,747
Categories: Conversion Aids
Article SummaryX
If you need to convert inches to millimeters, start by writing down your original measurement in inches without any fractions. Next, multiply that measurement by 25.4, since there are 25.4 millimeters in 1 inch. You can do this manually or use a calculator. The answer you get by multiplying those numbers is the converted measurement in millimeters. For tips on using a ruler to convert inches to millimeters, read on!
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