0.3125 as a Fraction of an Inch

Answer
5/16 in
0.3125 in = 5/16 in (1/64 in) = 7.9375 mm

0.3125 inches equals 5/16 inch, a widely used bolt, wrench, and socket size in automotive and general hardware work. It also serves as a common tap drill and wood dowel diameter. Sitting exactly between 1/4 in (0.25 in) and 3/8 in (0.375 in), it rounds to the same 5/16 in whether you use 1/16, 1/32, or 1/64 precision.

Try another decimal
Nearest 1/16
5/16"
Nearest 1/32
5/16"
Millimeters
7.9375 mm

Related values

ValueResult
Nearest 1/8 in3/8 in
Nearest 1/16 in5/16 in
Nearest 1/32 in5/16 in
Nearest 1/64 in5/16 in
Millimeters7.9375 mm
Centimeters0.7937 cm
Feet0.026042 ft

How the conversion works

  1. Split the decimal. Separate the whole-number part from the decimal part. 0.3125 has no whole-number portion, so the full value converts into the fraction.
  2. Multiply by precision. Multiply the decimal by the denominator you want, 16, 32, or 64, then round to the nearest whole number. 0.3125 × 16 = 5 exactly, with nothing to round off.
  3. Simplify. Reduce the fraction using the greatest common divisor of numerator and denominator. 5 and 16 share no common factor, so 5/16 is already fully reduced.
  4. Verify in mm. Multiply the decimal inches by 25.4 to double-check the metric value: 0.3125 × 25.4 = 7.9375 mm.

Frequently Asked Questions

0.3125 inches equals 5/16 in. That answer stays fixed at 1/16, 1/32, and 1/64 precision because 0.3125 is already an exact number of sixteenths.

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