Clothing sizes differ from store to store, but an even greater divide is how other countries determine clothing sizes. Jeans in particular can be measured in inches, centimeters, or using the American size chart. Converting between the sizes can be done by either directly measuring the waist or using an equation to change between already established sizes.
How to Convert Jean Sizes
Find the size of the jean. If you're converting from American jeans, the size with be an arbitrary number ranging from 00 to 16 with some variations for larger figured women. If you're starting with jeans from another country the size might be in inches or centimeters. Write the number down.
Convert centimeters into inches by dividing the number in centimeters by 2.54. For example, jeans that are listed as 74 centimeters would be converted to 29.1 inches. As a rule of thumb, if the size listed is over 60 the units are in centimeters. Less than 60 are generally inches.
Convert the inches to American sizes by subtracting 21 from the size in inches. Jeans that are listed as a size 30 would be converted to a size 9.
Reverse the conversion by adding 21 to a standard women's size. Having an American size of 4 would be converted to a size 25 if inches are the unit of measurement.
Determine the size in centimeters (if needed) by multiplying the size in inches by 2.54. A size of 25 inches would be 63.5 centimeters after conversion.
Much like in America, jeans of the same size can still have different fits. Keep this in mind when ordering jeans online or trying them on.