Inch Fraction Calculator – Find Inch Fractions From Decimal and Metric Measurements

Convert inch fractions to decimal, convert decimal to inch fractions, convert inches to metric measurements, convert metric measurements to inch fractions, and convert to feet automatically.

Inch Fraction, Decimal, and Metric Results

Imperial Units

Metric Units

Inch Fraction to Decimal Conversions

The chart below can be used to easily find the correct fraction for your decimal measurement, or vice-versa. Find decimal equivalents in 1⁄64" increments, including 1⁄2", 1⁄4", 1⁄8", and 1⁄16", and 1⁄32" measurements.

The chart also shows hints on the markings sizes found on a tape measure or ruler.

Inch fraction to decimal inches conversion chart showing the decimal values for inch fractions in quarter inch, eight inch, thirty-second inch, and sixty-fourth-inch increments

How to Calculate Inch Fractions

Inch fractions use denominators that are powers of 2 and go up to the 64th of an inch. That means the fraction denominators will be 2, 4, 8, 16, 32, and 64. As a result, converting a decimal to an inch fraction is not as simple as finding the nearest fraction.

Instead, it is necessary to find the nearest fraction with the denominator that is a power of 2, also known as a dyadic fraction or dyadic rational number.[1] Typical inch fractions will look something like 1/64, 1/32, 1/16, 1/8, 1/4, or 1/2. Use our feet and inches calculator to add or subtract feet and inch fractions.

Finding Inch Fractions on a Tape Measure

Diagram showing inch fractions on a tape measure, distinguished by the size of the tick mark

Finding measurements on a ruler or tape measure can be confusing at first, but once you understand how the marks are laid out, then it is far simpler. The markings between the larger inch numbers vary in length.

The longest markings will be the quarter inch markings, i.e. the first marking is 1/4 inch, the second is 1/2 (2/4) inch, the third is 3/4 inch.

The next longest markings will be the eighth-inch markings, i.e. the first marking is 1/8 inch, the second is 3/8 inch, the third is 5/8 inch, etc.

The next longest markings will be the sixteenth-inch markings, i.e. the first marking is 1/16 inch, the second is 3/16 inch, the third is 5/16 inch, etc.

Image of a ruler showing the inch fraction values of the tick marks

Download a free printable ruler with fraction measurements marked to help learn how to find the inch fractions for a measurement and for easy reading.

Converting Inches to Metric Measurements

Inch Fraction Conversion Chart – Fraction Decimal and Metric Equivalents

See equivalent length measurements in fraction, decimal, and metric up to one inch in 1⁄64" increments. Use this to convert decimals to inches and millimeters.

Inch fractions to the 1/64 of an inch and the equivalent decimal values in inches and metric values in millimeters
Fraction
(inches)		 Decimal
(inches)		 Metric
(millimeters)
1/64″ 0.015625″ 0.396875 mm
1/32″ 0.03125″ 0.79375 mm
3/64″ 0.046875″ 1.190625 mm
1/16″ 0.0625″ 1.5875 mm
5/64″ 0.078125″ 1.984375 mm
3/32″ 0.09375″ 2.38125 mm
7/64″ 0.109375″ 2.778125 mm
1/8″ 0.125″ 3.175 mm
9/64″ 0.140625″ 3.571875 mm
5/32″ 0.15625″ 3.96875 mm
11/64″ 0.171875″ 4.365625 mm
3/16″ 0.1875″ 4.7625 mm
13/64″ 0.203125″ 5.159375 mm
7/32″ 0.21875″ 5.55625 mm
15/64″ 0.234375″ 5.953125 mm
1/4″ 0.25″ 6.35 mm
17/64″ 0.265625″ 6.746875 mm
9/32″ 0.28125″ 7.14375 mm
19/64″ 0.296875 7.540625 mm
5/16″ 0.3125″ 7.9375 mm
21/64″ 0.328125″ 8.334375 mm
11/32″ 0.34375″ 8.73125 mm
23/64″ 0.359375″ 9.128125 mm
3/8″ 0.375″ 9.525 mm
25/64″ 0.390625″ 9.921875 mm
13/32″ 0.40625″ 10.31875 mm
27/64″ 0.421875″ 10.715625 mm
7/16″ 0.4375″ 11.1125 mm
29/64″ 0.453125″ 11.509375 mm
15/32″ 0.46875″ 11.90625 mm
31/64″ 0.484375″ 12.303125 mm
1/2″ 0.5″ 12.7 mm
33/64″ 0.515625″ 13.096875 mm
17/32″ 0.53125″ 13.49375 mm
35/64″ 0.546875″ 13.890625 mm
9/16″ 0.5625″ 14.2875 mm
37/64″ 0.578125″ 14.684375 mm
19/32″ 0.59375″ 15.08125 mm
39/64″ 0.609375″ 15.478125 mm
5/8″ 0.625″ 15.875 mm
41/64″ 0.640625″ 16.271875 mm
21/32″ 0.65625″ 16.66875 mm
43/64″ 0.671875″ 17.065625 mm
11/16″ 0.6875″ 17.4625 mm
45/64″ 0.703125″ 17.859375 mm
23/32″ 0.71875″ 18.25625 mm
47/64″ 0.734375″ 18.653125 mm
3/4″ 0.75″ 19.05 mm
49/64″ 0.765625″ 19.446875 mm
25/32″ 0.78125″ 19.84375 mm
51/64″ 0.796875″ 20.240625 mm
13/16″ 0.8125″ 20.6375 mm
53/64″ 0.828125″ 21.034375 mm
27/32″ 0.84375″ 21.43125 mm
55/64″ 0.859375″ 21.828125 mm
7/8″ 0.875″ 22.225 mm
57/64″ 0.890625″ 22.621875 mm
29/32″ 0.90625″ 23.01875 mm
59/64″ 0.921875″ 23.415625 mm
15/16″ 0.9375″ 23.8125 mm
61/64″ 0.953125″ 24.209375 mm
31/32″ 0.96875″ 24.60625 mm
63/64″ 0.984375″ 25.003125 mm
1″ 1.0″ 25.4 mm

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References

  1. The Free Dictionary, dyadic rational, https://encyclopedia2.thefreedictionary.com/Dyadic+rational+number