What rating system does the Play Magnus app use? I played a total of 261 games against the Play Magnus app at different ages. My overall score is 144 wins, 99 losses and 16 draws. My last game was against the 10-year-old Magnus. Prior to the start of the game I was rated 1248. I won the game and my rating increased by an astonishing 133 points, so I was wondering what is the rating system used.

Most weird is that I sometimes draw against a far higher rated Magnus and lose rating points (I once drew 26-year-old Magnus and lost 18 rating points when I was rated only 1486). Is there any explanation for that, or is it a bug in the app?
This is a list of Magnus Carlsen’s ratings at each of his birthdays.


9 years old: 900
Norwegian rating.
10 years old: 1645
Still Norwegian rating.
11 years old: 2127
FIDE rating now.
12 years old: 2250
Magnus became an FM at age 11.
13 years old: 2450
Magnus became an IM at age 12.
14 years old: 2581
Magnus became a GM at age 13, the youngest in the world and the second youngest ever at the time.
15 years old: 2570
Magnus went through his only real slump that year.
16 years old: 2698
Magnus played in his first super tournaments right around this time.
17 years old: 2714
Magnus reached 2700 at 16 as the youngest ever, a record that has since been beaten by Wei Yi.
18 years old: 2786
Magnus was now number four in the world.
19 years old: 2801
Magnus reached 2800 at 18 as the youngest ever. The record still stands.
20 years old: 2802
Magnus became the highest rated player in the world at 19, as the youngest ever.
21 years old: 2826
Magnus solidified his top spot on the world rankings this year, and has held it since.
22 years old: 2848
Magnus was really closing in on Kasparov’s rating record now, and surpassed it shortly after his 22nd birthday.
23 years old: 2870
At this point there was a whopping 70 point difference between Magnus and the second rated player, Aronian.
24 years old: 2863
Magnus peaked at 2882 (unofficially 2889) that year, the highest rating ever.
25 years old: 2850
A minor dip in form.
26 years old: 2853
Still number one by a good margin.


About the app - of course there may be flaws, concerning its system there is no information. Although I don't see any reason why they would deviate from the ELO system (which is used in official FIDE games), whose formulas aren't secret and can be found even on Wikipedia.