Turn decimal measurements into marks your tape can show.

How decimal-to-fraction conversion works

Separate the whole inches from the decimal remainder. Multiply that remainder by the chosen denominator, round to the nearest whole numerator, and reduce the fraction when possible. The denominator represents the smallest graduation you intend to use: eighths for rough work, sixteenths for common tape-measure layout, or thirty-seconds and sixty-fourths for finer comparison.

For 5.4375 inches at a sixteenth-inch denominator, the whole number is five and the remainder is 0.4375. Multiplying by 16 gives exactly seven, so the result is 5 7/16 inches. Because seven and sixteen have no common factor, the fraction is already reduced.

Choose precision that matches the work

More digits do not automatically create a more accurate installation. A flexible tape, thick pencil line, paper template, rough wall, and hand-held drill all limit useful precision. Choose a fraction small enough for the hardware tolerance and method, but not so small that the mark implies control the process does not have.

When a decimal does not land exactly on the chosen denominator, the result is rounded. PrintJig reports the practical fraction and equivalent measurements so you can decide whether the rounding difference matters. For paired holes and manufactured parts, verify against the physical item rather than relying only on a converted catalog value.

Convert millimeters and inches carefully

One inch equals exactly 25.4 millimeters. Divide millimeters by 25.4 to obtain decimal inches; multiply inches by 25.4 to obtain millimeters. Only after converting to inches should you round to a workshop fraction.

For example, 128 mm is approximately 5.0394 inches. At a sixteenth-inch denominator that rounds to 5 1/16 inches, but the rounded fraction is not physically identical to 128 mm. Cabinet pulls commonly use metric center-to-center dimensions, so entering 128 mm directly is safer than replacing it with a nearby inch fraction when the holes must align.

Avoid cumulative rounding

Repeated layouts should keep calculations at full precision and round only the final marks. If an equal-spacing result advances by a repeating decimal, measuring every new item from the previous rounded mark can accumulate error. Use the calculator's individual center positions measured from the original reference edge.

1. Keep the source measurement in its original unit when possible.
2. Select the denominator your measuring tool can resolve.
3. Review the decimal and metric equivalents before accepting the fraction.
4. Mark every repeated position from one fixed reference.
5. Check the final span or physical hardware before drilling or cutting.

Fractions are a communication choice

A fraction makes a measurement easier to find on a traditional tape. It does not change the underlying size. Keep metric dimensions for metric hardware, decimal dimensions for machine settings, and fractions for physical layout when that is the clearest way to work.