(revision 1.2)

Club (ELO) Rating

The Sykes Red Knights (SRK) ELO rating is different from the Chess.com (CdC) rating. Our club’s rating will be independent from Chess.com rating. The SRK ELO rating (SRKE) has a beginning value of 1400 for new members. The CdC rating (CdCR) begins at 1200 (from the blogs), although I recall I had my rating at 1300 when I registered.

As you play ranked/official games with other club members, your SKRE will either go up if you win or go down if you lose. The increase or decrease will depend on:
a. The SRKE of your opponent.
b. Your rank.

WARNING: Mind boggling stuffs below!

The formula to calculate your new rating is as follows;
R’A = RA + K(SA – EA)

Where:
RA - True strength
K – K-factor
SA – Actual score
EA – Expected score which has the formula;
1
EA = -----------------------
1 + 10 to the power ((RB-RA) / 400)

Now, if you ask me... I don’t have any idea what the heck is going on at the above formula, and I don’t have any idea how those math guys came up with it! (LOL) But, let’s break it down and not over complicate things.

K-factor:
Let’s discuss first the K-factor. The K-factor is... I don’t know... K-coefficient... It’s for math guys (LOL). Let’s just define it as the amount to boost (multiplier) your rank

We’re going to use the USCF (United States Chess Federation) K-factors; 32, 24, and 16. Why? Well, it’s larger than the FIDE ones; 30, 15 and 10 (LOL).

So how does it work? The K-factor that you get will depend on your current rank or its equivalent strength. See below list;

32 (K-factor) – Given to players with 2199 and below rating or has Normal ranking
24 (K-factor) – Given to players with 2200 to 2499 rating or has Master ranking
16 (K-factor) – Given to players with 2500 and above rating or has Grand Master ranking

Ok, now maybe you’re wondering, “how do I rank?” Well, as a side track, I listed the rankings below for your reference:

999 & below: Rank F
1000 - 1199: Rank E
1200 - 1399: Rank D
----
1400 - 1599: Rank C
1600 - 1799: Rank B
1800 - 1999: Rank A
2000 - 2199: Expert
2200 - 2299: Candidate Master
2300 - 2399: National Master
2400 - 2499: International Master
2500 - 2699: Grand Master
2700 & above: Super Grand Master

As mentioned before, new members have 1400 ELO rating or Rank C status. You may be familiar with those “Master” titles. They are used by various chess organization. I just consolidated all those cool sounding titles so we can brag about them during meetings/get together! (LOL) I’ll discuss the prizes/awards you’ll get, when you reach those ranks, on a separate topic.

Win/Lose probability:
Moving on, let’s discuss the “Expected score” or as I call it: “Winning probability” or “Win/Lose probability”. Why did I call it like that? Because it’s the actual win/lose percentage you get based on your rank and your opponent’s rank.

Again, that formula above for EA is a pain so let’s just have a table for our Win/Lose probability. Refer to the table below:

Rating Difference	Stronger Win-Lose	Weaker Win-Lose
0 to 24	0.5	0.5
25 to 49	0.53	0.47
50 to99	0.57	0.43
100 to 149	0.64	0.36
150 to 199	0.7	0.3
200 to 249	0.76	0.24
250 to 299	0.81	0.19
300 to 349	0.85	0.15
350 to 399	0.89	0.11
400 and above	0.92	0.08

I got this table from FIDE, so now, we are a mix of FIDE and USCF standards! (LOL)

We will refer to the above table when we compute your new ranking. First the Rating Difference, that value is computed by subtracting your rating and your opponent’s rating (or vice versa, whoever is the highest).

a. Example:

1400 – My rating
- 1400 – My opponent’s rating
-------
       0 – Rating Difference

My Win/Lose probability is 0.50
My opponent’s Win/Lose probability is also 0.50

b. Another example:

1416 – My opponent’s rating
- 1400 – My rating
-------
     16 – Rating difference

My Win/Lose probability is 0.50
My opponent’s Win/Lose probability is also 0.50

c. And yet another example:

1447 – My rating
- 1400 – My opponent’s rating
-------
     47 – Rating difference

My Win/Lose probability is 0.53 since I have the stronger rating
My opponent’s Win/Lose probability is also 0.47 since he/she is weaker in rating

Actual score:
And lastly, the actual score. That actual score is either 0, 0.5 or 1, your score in the game (0 – lose, 0.5 – draw, 1 – win).

All together now!
Alright! Hope you guys got all the items I discussed. Now let’s consolidate what we learned.

From the formula above R’A = RA + K(SA – EA) let’s make it more readable:
New Rating = Old Rating + K-factor (Actual Score – Win/Lose probability) {Now that’s more like it! }

Let’s use example c (1447 – my rating and 1400 – opponent’s rating). The scenario is, I won the game and let’s try out our formula.

Computing my rating:
1447 has a K-factor of 32

1447 – My rating
- 1400 – My opponent’s rating
-------
47 – Rating difference – 0.53 Win/Lose probability (I’m stronger)

1447 + 32(1-0.53) = New rating
1447 + 32(0.47) = New rating
1447 + 15.04 = 1462.04
1462 – New rating (rounding it off to the nearest 1s)

Computing my opponent’s rating:
1400 has a K-factor of 32

1447 – My rating
- 1400 – My opponent’s rating
-------
47 – Rating difference – 0.47 Win/lose probability (He/she’s weaker)

1400 + 32(0-0.47) = New rating
1400 + 32(-0.47) = New rating
1400 - 15.04 = 1384.96
1385 – New rating (rounding it off to the nearest 1s)

So that concludes SRKE computation. Remember that this is how we will compute your ratings on ranked games. I will discuss how to secure ranked games on another topic.

Thanks!

Sykes Red Knights

Super Admins