Fraction to decimal inches calculator

Convert tape-measure fractions to decimals and millimeters, and back.

How it works

Tape measures and many US box specs use fractions of an inch, while CAD files, dielines and international suppliers use decimals or millimeters. Divide the numerator by the denominator and add the whole inches: 5 3/8 in = 5.375 in = 136.53 mm.

For the other direction, enter a decimal and the calculator rounds to the nearest sixteenth and thirty-second, the finest markings on most tape measures. For whole box sizes, use the box dimensions converter.

Results are estimates based on typical industry values. Confirm final specifications with your supplier or carrier.

Frequently asked questions

What is 3/8 inch as a decimal?

0.375 inch, or 9.525 mm.

What is 0.625 inch as a fraction?

5/8 inch.

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