0.125 as a Fraction of an Inch

Answer
1/8 in
0.125 in = 1/8 in (1/64 in) = 3.175 mm

0.125 inches equals 1/8 inch, a size you will find on nearly every hardware store shelf. It is the nominal thickness of thin plywood and hardboard panels, a standard fractional drill bit, and a common socket and hex key size. Because 0.125 is an exact eighth, it stays 1/8 in whether you round to 1/16, 1/32, or 1/64 precision, and it sits exactly halfway between 0.0625 in (1/16 in) and 0.25 in (1/4 in).

Try another decimal
Nearest 1/16
1/8"
Nearest 1/32
1/8"
Millimeters
3.175 mm

Related values

ValueResult
Nearest 1/8 in1/8 in
Nearest 1/16 in1/8 in
Nearest 1/32 in1/8 in
Nearest 1/64 in1/8 in
Millimeters3.175 mm
Centimeters0.3175 cm
Feet0.010417 ft

How the conversion works

  1. Split the decimal. Separate the whole-number part from the decimal part. 0.125 has no whole-number portion, so the full value goes into the fraction calculation.
  2. Multiply by precision. Multiply the decimal by the denominator you want, 16, 32, or 64, then round to the nearest whole number. 0.125 × 16 = 2 exactly, with no rounding needed.
  3. Simplify. Reduce the fraction using the greatest common divisor of numerator and denominator. 2/16 shares a factor of 2, so it simplifies to 1/8.
  4. Verify in mm. Multiply the decimal inches by 25.4 to check the metric value: 0.125 × 25.4 = 3.175 mm.

Frequently Asked Questions

0.125 inches equals 1/8 in. This holds true at 1/16, 1/32, and 1/64 precision since 0.125 divides evenly into eighths with nothing left to round away.

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