Millimeters to Inches Converter

Millimeters to Inches Converter

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Formula: multiply millimeters by 0.0393701 to get inches

How to convert millimeters to inches

To convert millimeters to inches, multiply the number of millimeters by 0.0393701. For example, 25.4 mm × 0.0393701 = 1 inch exactly. Going the other way, multiply inches by 25.4 to get millimeters.

Since 1 inch = 25.4 mm exactly, 1 mm = 1 ÷ 25.4 = 0.03937 inches. Millimeters are commonly used in engineering, manufacturing, woodworking, and medical devices.

This conversion is particularly useful for tool sizes, drill bits, pipe diameters, screen sizes, and any precision measurement that needs to be expressed in both metric and imperial units.

Millimeters to inches conversion table

Millimeters (mm) Inches (in) Fraction (approx)
1 mm0.03937 in≈ 1/32 in
2 mm0.07874 in≈ 5/64 in
3 mm0.11811 in≈ 1/8 in
4 mm0.15748 in≈ 5/32 in
5 mm0.19685 in≈ 13/64 in
6 mm0.23622 in≈ 15/64 in
8 mm0.31496 in≈ 5/16 in
10 mm0.39370 in≈ 3/8 in
12 mm0.47244 in≈ 15/32 in
15 mm0.59055 in≈ 19/32 in
20 mm0.78740 in≈ 25/32 in
25 mm0.98425 in≈ 63/64 in
25.4 mm1.00000 in= 1 inch exactly

Frequently asked questions

How many mm in an inch?
1 inch = exactly 25.4 millimeters. This is the internationally defined standard since 1959.
How many inches is 10 mm?
10 mm = 0.3937 inches. This is just under 13/32 of an inch, or approximately 3/8 of an inch.
How many inches is 25 mm?
25 mm = 0.984 inches — just under 1 inch. 25.4 mm is exactly 1 inch.
How many mm is ½ inch?
½ inch = 12.7 mm. Calculation: 0.5 × 25.4 = 12.7 mm.
How many mm is ¼ inch?
¼ inch = 6.35 mm. Calculation: 0.25 × 25.4 = 6.35 mm.