How Ratings are calculated

Rn =  Ro + K (W – We)

Rn New rating
  Ro Old rating
  K Value of a single game –30    between 20 and 40…
    K = 10 if rating > 2400
    K = 15 if rating under 2400
    K = 25 for players new to the rating list, until they have completed events with a total of at least 30 games;
    W Score; 1.0 for a win, 0.5 for a draw
  We Expected score based on Ro

Rating difference	Winning Expectancy
736+	100%
735	99%
500	96%
450	94%
400	92%
350	89%
300	85%
250	81%
200	76%
150	70%
100	64%
50	57%
25	53%
0	50
-25	47%
-50	43%
-100	36%
-150	30%
-200	24%
-250	19%
-300	15%
-350	11%
-400	8%
-500	4%
-735	1%
-736+	0%