grammatical number - Which one is correct: 1yr or 1yr. or 1 yr . . . In this case, you could use 1 yr , 2 yr and the abbreviation would always be correct As reported from the Oxford Dictionary of English, it's the same in British English, except the abbreviation is written without a period at the end (e g yr instead of yr ) As the other answers says, there should be a space between the number and yr yrs