What is the correct abbreviation for inches?

Answer 1

The abbreviation for inches is "in." Note that this is the only measurement unit abbreviation that uses a period. The Système International d'Unités (SI) does not use periods after any such abbreviations, but "in." is often/usually recommended so as to avoid confusing it with "in" the preposition. The abbreviation for feet is not ft.; ft is proper, as is lb, mm, km, etc. Note also that singular and plural forms are the same. Despite what you see at the grocery store, the abbreviation for pounds is not "lbs".

Example: 2 in. is the abbreviation for 2 inches.

For shorthand, symbols are commonly substituted for letter abbreviations.

Example: 5 foot, 3 inches in height can be written as 5'3".

However, this practice is usually discouraged in technical/scholarly literature. Note that the shorthand symbols are NOT apostrophes or quotation marks, which are curved. These are prime and double prime marks, which are straight.