https://www.chess.com/article/view/chess-ratings---how-they-work
how are ratings calculated?
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Very short answer is you gain some fraction of 20 points for winning a game. How large depends on the rating.
Beating someone equal to your rating, you get 50% i.e. you gain 10 rating points. Beating a person rated 200 points below you gains about 5 rating points. Beating a person rated 200 points above you gains about 15.
The ratings of new players are considered unreliable, and they have a multiplier. So for your first game you might gain or lose 100 points. For your 2nd game, the multiplier will be less, and so on, until after maybe 20 or 30 games it's as I described above, you will gain and lose some fraction of 20.
How are ratings calculated