Inch Fraction Calculator - Decimal to Inches (2024)

Convert inch fractions to decimal, decimal to inches, inches to metric measurements, metric measurements to inch fractions, and inches to feet using our inches to fraction calculator.

How to Calculate Inch Fractions

Measurements in inches can be expressed as a decimal or a fraction. When inches are expressed as a fraction, there are some special rules to follow, which are important to know to convert a decimal to inches correctly.

While fractions of an inch can be represented as any standard fraction, the most common fractions of an inch use denominators that are powers of 2, from half inches to up to the 64ths of an inch. That means the fraction denominators are most commonly 2, 4, 8, 16, 32, and 64.

These specific fractions of an inch are referred to as inch fractions.

As a result, if we want to convert a decimal to one of these inch fractions, then know that converting a decimal to an inch fraction is not quite the same as converting a decimal to a regular fraction.

Instead, some minor rounding will occur since it will be 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.

When you’re working with larger measurements, you can use our feet and inches calculator to add or subtract feet and inch fractions.

How to Convert Inches to Fraction

To convert decimal inches to an inch fraction, you’ll need to round the decimal portion to the nearest dyadic fractional inch.

First, separate the whole number from the decimal; these are the whole inches. Then, take the remaining portion of the decimal to the right of the decimal point and multiply it by the denominator of the level of precision you need (e.g., 1/16, 1/32, or 1/64).

For instance, to round to the nearest 1/16, take the decimal portion and multiply it by 16. Then, round the result to get the numerator of the inch fraction.

Finally, place the numerator over the level of precision, 16 in this case. Then, put the fractional inches next to the whole inches for the final result.

Decimal to Inches Chart

Use this decimal to inches chart to easily find the correct fraction for your decimal measurement or to convert inches to fraction. Find decimal equivalents in ¹⁄₆₄” increments, including ¹⁄₂“, ¹⁄₄“, ¹⁄₈“, ¹⁄₁₆“, and ¹⁄₃₂” measurements.

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

How to Convert Inch Fractions to Decimal

Converting an inch fraction to decimal inches is as easy as dividing the fraction. Divide the top number (numerator) by the bottom number (denominator) to find the value in inches as a decimal.

You can also use a fraction to decimal calculator or the chart below.

Inches to Decimal Chart

The inch fraction to decimal and metric chart below shows equivalent length measurements in fraction, decimal, and millimeters up to one inch in ¹⁄₆₄” increments. You can use this to convert inches to decimal or millimeters.

How to Convert Inches to Metric Measurements

To convert inch fractions to metric measurements, you need to keep in mind that there are 2.54 centimeters or 25.4 millimeters per inch.

So, to convert an inch fraction to centimeters, you multiply the inches by 2.54, and to convert to millimeters, multiply by 25.4.

cm = in × 2.54
mm = in × 25.4

You can also use a length converter such as an SAE to metric converter.

How to Find Inch Fractions on a Tape Measure

Finding measurements on a ruler or tape measure can be confusing at first, but once you understand how the marks are laid out, then you’ll see it is quite simple. Notice that the markings between the whole-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, and 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 smallest 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.

We also have a free printable ruler with fraction measurements marked to help you learn how to find the inch fractions for a measurement. If you need measurements more precise than 64ths of an inch, then you will need to use a more accurate measuring tool such as calipers.

Frequently Asked Questions

What is an inch fraction?

An inch fraction is a fraction of an inch with a denominator that is a power of two. For example, 1/2, 3/8, 15/16, 17/32, and 33/64 are all examples of inch fractions.

How big is one inch?

If you are more familiar with the metric system, one inch is equal to 25.4 millimeters or 2.54 centimeters. If not, a standard paperclip is one inch long, and the diameter of a U.S. quarter is also approximately one inch.

Do you use decimals or fractions for inches?

You can use either decimals or fractions when representing portions of an inch. Typically we use fractions when the portion of an inch equals one of the common inch fractions in the list above.

Why does the U.S. use inches?

What is the symbol for inches?