Convert millimeters to inches, both ways.
Type millimeters and read the exact inches, or type inches to convert back to millimeters. The result updates live, with the nearest fractional inch, centimeters and feet for context and a one-click copy.
Your value
Edit either box. The formula is inches = mm divided by 25.4, and mm = inches times 25.4.
0.9843 inWhat this means
Common mm to inches values
| Millimeters | Inches | Nearest fraction | Rough guide |
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How the conversion works
Conversion Factor
1 millimeter equals 0.03937 inches. Equivalently, 1 inch = 25.4 mm exactly. Multiplying mm by 0.0394 gives inches; dividing mm by 25.4 is more memorable.
Common Uses
Engineering drawings use millimeters worldwide. US workshops often need to convert to inches for fractional measurements. Jewelry, watchmaking, and machining commonly need precise mm to inch translation.
Reference Values
1 mm = 0.039 in. 10 mm = 0.394 in. 25 mm = 0.984 in (≈ 1 in). 50 mm = 1.969 in. 100 mm = 3.937 in.
Common questions
How many inches is 25 mm?
25 mm equals 0.9843 inches, just under 1 inch.
What's a typical screen thickness in mm and inches?
Phone screen ~7 mm = 0.276 in. Tablet ~6 mm = 0.236 in. Laptop ~15 mm = 0.591 in.
How do I convert fractional inches?
Convert the fraction to decimal (e.g. 1/8 = 0.125), then multiply by 25.4 to get mm. Or use this calculator in reverse direction.
All conversion runs in your browser. Nothing is uploaded. 1 inch is exactly 25.4 mm by international definition, so these results are precise, not approximate.