https://leagueoflegends.fandom.com/wiki/Experience_(summoner)The following formulas are for experience gained from Summoner's Rift as of November 17, 2017:[2]
General formula:
TIME: the total number of seconds elapsed in a game (e.g. 15:49 => 949 seconds).
EXPERIENCE = (TIME × (XP/s) + Base XP) (rounded to nearest integer)
If the game is won:
EXPERIENCE = (TIME × 0.11 + 6.6)
If the game is lost:
EXPERIENCE = (TIME × 0.09 + 5.4)
Co-op vs AI
The experience gained for Co-op vs. AI games is reduced for Summoners with level 10 or higher.[3]
Summoner Level 1-9: Bots grant 100% XP.
Summoner Level 10-19: Bots grant 90% XP.
Summoner Level 20-29: Bots grant 80% XP.
Summoner Level 30+: Bots grant 75% XP.