MM to In: The Direct Answer
One millimeter equals 0.03937 inches. That is the exact conversion for mm to in: divide millimeters by 25.4, because 1 inch is defined as exactly 25.4 millimeters.
Quick Answer: Inches = millimeters / 25.4. So 10 mm = 0.39 inches, 25.4 mm = 1 inch, and 100 mm = 3.94 inches.
Millimeters are used in engineering, manufacturing, photography and metric measurements around the world. Inches are used in the United States for everyday length. Converting between them is a daily task, from reading a ruler to checking a screw size or a screen dimension.
MM to In Conversion Chart
| Millimeters | Inches | Millimeters | Inches |
|---|---|---|---|
| 1 mm | 0.04 in | 30 mm | 1.18 in |
| 5 mm | 0.20 in | 40 mm | 1.57 in |
| 10 mm | 0.39 in | 50 mm | 1.97 in |
| 12.7 mm | 0.50 in | 75 mm | 2.95 in |
| 15 mm | 0.59 in | 100 mm | 3.94 in |
| 20 mm | 0.79 in | 150 mm | 5.91 in |
| 25 mm | 0.98 in | 200 mm | 7.87 in |
| 25.4 mm | 1.00 in | 300 mm | 11.81 in |
In to MM: The Reverse Conversion
To convert inches to millimeters, multiply by 25.4. One inch is 25.4 mm, 2 inches are 50.8 mm, and 12 inches, or 1 foot, are 304.8 mm. This direction is just as common, for example when a US product specification must be given in metric units.
Common MM to In Sizes
A standard pencil is about 7 mm wide, or 0.28 inches. A US dime is about 1.35 mm thick, or 0.05 inches. A credit card is about 0.76 mm thick. A 3.5 mm headphone jack, a familiar size, is 0.14 inches. Knowing a few everyday sizes helps you check a conversion at a glance.
How to Convert Without a Calculator
For a quick estimate, divide millimeters by 25. For a precise answer, divide by 25.4. The difference is small for short lengths: 100 mm estimated is 4 inches, while the exact answer is 3.94 inches. For engineering or manufacturing work, always use 25.4.
Related Conversions
For more everyday measurement help, see how many cups in a quart, how many cups in a pint and how many cups in a gallon.
Frequently Asked Questions
How many inches in 1 mm?
0.03937 inches.
How many mm in 1 inch?
25.4 mm, exactly.
How do you convert mm to in?
Divide by 25.4.
What is 10 mm in inches?
0.39 inches.
What is 100 mm in inches?
3.94 inches.
Is 25 mm the same as 1 inch?
Almost: 25 mm is 0.98 inches. Exactly 1 inch is 25.4 mm.
Conclusion
To convert mm to in, divide by 25.4. Remember 25.4 mm = 1 inch, and every millimeter-to-inch conversion follows from it.
Source: Millimetre – Wikipedia