mm to inch Conversion Table

Millimeters and inch fractions are often used to identify dimensions of small objects, drill bit and wrench sizes, thickness of various construction materials, etc.
Here are the steps to convert a value in millimeters to an inch fraction:

1. Divide the value in millimeters by 25.4 to obtain a decimal inch value;
2. If the result is greater than 1, subtract the whole number (the integer part) from the decimal value;
3. Multiply the the remaining fractional part by 64;
4. Round the product to the nearest whole number;
5. Express the result as a fraction with the rounded number as the numerator and 64 as the denominator. Simplify the fraction, if required;
6. Express the final result by combining the whole number and the fraction obtained from the previous steps.

It is important to keep in mind that the converted value is often an approximation and may not be an exact representation of the original value. This is because the nearest 1/64 inch fraction is used to represent the converted value, which may not be an exact representation of the original millimeter value. More accurate result can be obtained by using a denominator of 128 in the step 3 above, or switching to more precise units of measurement, such as thou or mil.

For example, convert 28.5 mm to an inch fraction:

1. 28.5 / 25.4 = 1.122047 (decimal inch value);
2. 1.122047 - 1 = 1.122047 (remaining fractional part);
3. 0.122047 * 64 = 7.811008;
4. 7.811008 rounded to the nearest whole number is 8;
5. 8/64 = 1/8 (expressed as a fraction and simplified);
6. The final result is 1 1/8.

Note the difference between the decimal inch value for 1 1/8 equal to 1.125000 and the value of 1.122047 from the step 1 above.