мне ... год

Phrase

 * 1) I'm ... year(s) old

Usage notes
Use the appropriate case of год after simple or compound numbers ending in оди́н (1), два (2), три (3), or четы́ре (4), except for 11, 12, 13 and 14 (and 111 - 114, 211 - 214 etc.) - for these and all other numbers, and with adverbs of quantity (мно́го, ско́лько, etc.), use the appropriate case of лето.

To summarize:
 * год — for most numbers ending in 1
 * года — for most numbers ending in 2, 3 or 4
 * лет — for most numbers ending in 5, 6, 7, 8, 9 and 0, as well as all the teens.