How do I convert a decimal to a fraction of an inch?

Multiply the decimal by the denominator you want (for example 16), round to the nearest whole number, then place it over that denominator and reduce. 0.625 in x 16 = 10, so 0.625 in = 10/16 = 5/8 in.

How many millimeters are in one inch?

One inch equals exactly 25.4 millimeters.

How do I convert millimeters to a fraction of an inch?

Divide the millimeters by 25.4 to get decimal inches, then round to the nearest usable fraction such as 1/16, 1/32 or 1/64.

Which fraction precision should I use?

Use 1/16 inch for carpentry and tape measures, 1/32 for cabinetry, 1/64 for metalwork and CNC setup, and 1/128 to 1/256 for high-precision machining.

Inch Fraction, Decimal & mm Converter

Convert fractions, decimals, percent, millimeters, feet & inches, and circle dimensions — five tools in one. Snap to any precision from 1/16 to 1/256. Click any result to copy.

Decimal · Percent · Fraction

Type a value in any form — get the other two.

Enter a decimal, percent, or fraction

Decimal

0.625

Percent

62.5%

Fraction (1/16")

5/8

Common values — click to load

Detects format automatically: a slash means fraction (5/8), a percent sign means percent (62.5%), anything else is a decimal (0.625). The fraction is snapped to the nearest 16th of an inch, and the note shows which way it rounded and by how much.

Circle · radius & diameter

Enter any one measurement — get the rest.

Enter a measurement

This value is the…

Radius

Diameter

Circumference

31.4159

Area

78.5398

Diameter is twice the radius (d = 2r), circumference is 2πr, and area is πr². Pick which value you're typing, and the other three update live.

Feet + inches → total inches

Enter any parts you have — leave the rest blank.

Feet

Inches

Total inches

63.5

Inches (as fraction)

63 1/2

Decimal feet

5.291667

Millimeters

1612.9

Centimeters

161.29

Meters

1.6129

Total inches = feet × 12 + inches. The inches box accepts whole numbers, decimals, plain fractions like 1/2, or mixed numbers like 3 1/2. The fraction result is shown to the nearest 1/16 inch; metric uses 1 in = 25.4 mm.

Round to a fraction

Snap a measurement to the fraction you choose.

Enter a value

Round to

Direction

Rounded (fraction)

5/16

Rounded (decimal)

0.3125

Pick a fraction size, then a direction. Nearest rounds the usual way; Up always rounds away from zero; Down always toward zero. The result is shown in lowest terms.

Length units

Convert metric and imperial — fractions welcome.

From

Decimal places

All units

Type in either box — the other updates automatically. Pick units with the dropdowns; every other unit shows below as a box you can click to copy. Values take decimals or fractions (1 3/8). Based on 1 in = 25.4 mm.

Ideas and comments are welcome — email yankyh1652@gmail.com.