Elo Rating Change Calculator (FIDE)
Enter both ratings and the game result to see how many Elo points you gain or lose, using the official FIDE formula with the 400-point rule and your K-factor.
Formula
First, your expected score against this opponent:
E = 1 / (1 + 10^((Ropponent − Rplayer) / 400))
With equal ratings E = 0.50; a 200-point advantage gives about 0.76. FIDE's 400-point rule caps the rating difference at 400 points, so E stays between 0.09 and 0.91. Your rating change is then:
ΔR = K × (S − E)
where S is your actual score (1 win, 0.5 draw, 0 loss) and K is your K-factor:
- K = 40 — first 30 rated games, and juniors under 18 rated below 2300;
- K = 20 — standard for players rated under 2400;
- K = 10 — permanent once your rating has ever reached 2400.
Example: rating change at K = 20
| Opponent rating | Expected score | Win | Draw | Loss |
|---|---|---|---|---|
| 1300 | 0.76 | +4.81 | −5.19 | −15.19 |
| 1400 | 0.64 | +7.20 | −2.80 | −12.80 |
| 1500 | 0.50 | +10.00 | 0.00 | −10.00 |
| 1600 | 0.36 | +12.80 | +2.80 | −7.20 |
| 1700 | 0.24 | +15.19 | +5.19 | −4.81 |
At K = 40 all values double; at K = 10 they halve.
Frequently asked questions
How many points do I gain for beating an equal opponent?
Exactly half your K-factor: 10 points at K = 20, 20 at K = 40, 5 at K = 10. A draw changes nothing; a loss costs the same as a win gains.
What is the FIDE 400-point rule?
Any rating difference larger than 400 points is treated as exactly 400. This caps the expected score at 0.91, so the favourite still risks meaningful points and the underdog can gain close to the full K by winning.
Which K-factor should I choose?
K = 40 with fewer than 30 rated games, or under 18 and rated below 2300; K = 20 for established players under 2400; K = 10 once your rating has ever reached 2400 — permanently, even if it later drops.
Learn more in the guide: How FIDE Ratings Work