1 8th Inch in mm – Convert 1/8 Inch to Millimetres
1/8 inch = {formatNumber(MM, 4)} mm
One inch is defined internationally as exactly{' '} 25.4 millimetres . To convert a fraction of an inch to millimetres, first turn the fraction into a decimal, then multiply by 25.4:
Millimetre equivalents for common fractions of an inch:
Inches to millimetres converter (fractions supported)
How the calculation works
Fractions close to 1/8 inch
Frequently asked questions
More inches to millimetres conversions
What is 1/8 inch in mm?
1/8 inch equals 3.175 millimetres. The fraction 1/8 is 0.125 as a decimal, and 0.125 × 25.4 = 3.175 mm.
What is one eighth of an inch in millimetres?
One eighth of an inch is 3.175 mm. Because 1 inch = 25.4 mm exactly, one eighth is 25.4 ÷ 8 = 3.175 mm.
Is 0.125 inch the same as 3.175 mm?
Yes. 0.125 inch, 1/8 inch and "one eighth inch" all describe the same length, which converts to exactly 3.175 millimetres.
How do you convert 1 8th inch to mm?
Multiply 0.125 by 25.4 (the number of millimetres in one inch). The calculation is 0.125 × 25.4 = 3.175 mm. The calculator on this page handles any fraction or decimal the same way.
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