Stockfish level and its rating

Level 1: Skill -9, Depth 5, 50ms

Level 2: Skill -5, Depth 5, 100ms

Level 3: Skill -1, Depth 5, 150ms

Level 4: Skill 3, Depth 5, 200ms

Level 5: Skill 7, Depth 5, 300ms

Level 6: Skill 11, Depth 8, 400ms

Level 7: Skill 16, Depth 13, 500ms

Level 8: Skill 20, Depth 22, 1000ms

when you are playing A.I level 3, you are playing a stockfish that has only 0,15 seconds to make a decision, with articially reduced skill.

LiChess Stockfish ratings (LiChess rating, not ELO):

Level 1 = 800

Level 2 = 1100

Level 3 = 1400

Level 4 = 1700

Level 5 = 2000

Level 6 = 2300

Level 7 = 2700

Level 8 = 3000