What on Earth is ELO?

A Parent’s Guide to the Number That Actually Defines Your Child’s Chess Strength

So, you’ve mastered the "GPX" number (that’s the one for awards and selection). But now you’re looking at your child's profile and seeing a completely different set of numbers labeled Main, Standard, Rapid, and Blitz.

This is the Rating System (often called ELO). Unlike GPX, which resets every year, your Rating is a permanent badge of strength that follows your child throughout their chess career.

If GPX is "How well did you do this season?", ELO is "How likely are you to beat Magnus Carlsen right now?"

Here is the plain English breakdown of how it works, why it jumps around so much, and why it’s actually much "fairer" than GPX.

1. The Four Numbers on the Profile

When you log into Chess SA, you will see four distinct columns. Here is what they mean:

• Standard (S): The "Gold Standard." These are long games (60+ minutes). This is generally considered the most accurate measure of skill.
• Rapid (R): Faster games (10 to 59 minutes). Very popular in junior chess.
• Blitz (B): Super fast games (5 to 9 minutes). Pure chaos. Games under 5 minutes are not rated at all.
• Main (M): The Big One. This is a composite rating that updates every time your child plays any rated game (Standard, Rapid, or Blitz). This is usually the headline number used for seedings in tournaments.

2. The Math: "Did you do better than expected?"

Unlike GPX, which calculates an average, the Rating system is based on probability.

Before every game, the computer looks at the difference between your child and their opponent and calculates an Expected Score (We).

3. Why does my child's rating jump 50 points in a weekend?

You might notice your rating barely moves, but your 10-year-old’s rating swings wildly. This is due to the K-Factor.

The K-Factor is the "volatility" setting. It determines how fast a rating can change.

• K = 40: Assigned to new players and anyone rated under 1200. This allows kids to climb (or fall) very quickly to find their true level.
• K = 12: Assigned to masters (2400+). Their ratings are concrete and barely move.

Parent Tip: If your child loses 40 points in one tournament, do not panic. With a K-Factor of 40, they can win it back just as quickly next weekend.

4. The Safety Nets (Why ELO is nicer than GPX)

The Rating system has built-in safety features that the GPX system does not.

Safety Net #1: The "Weighted Rating" Buffer

Chess SA doesn't just look at your child's current rating ("Raw Rating"). They also calculate a "Weighted Rating"—an average of their last 24 rating updates.

The Rule: The "Published Rating" (the one on the website) is always the HIGHER of the two.

What this means: If your child has a disastrous tournament and their raw rating tanks, the website might still show a higher number because their historical average holds them up. It prevents one bad day from ruining their status.

Safety Net #2: The Rating Floor

Your child’s rating cannot drop more than 500 points below their highest-ever rating. This prevents sandbagging (losing on purpose to get a lower rating).

5. The "Time Weight" (Tw): ELO vs. GPX

This is the most confusing part for parents. Both systems use "Time Weighting," but they use it differently.

• In GPX: Rapid games are PENALIZED. A win in Rapid is worth 33% of a win in Standard. It drags your average down.
• In ELO: Rapid games are DAMPENED.
  • A Standard game (60/60) counts for roughly 83% to 100% of the potential rating change.
  • A Rapid game (10/10) counts for only roughly 29% of the potential rating change.

The Difference: In ELO, playing Rapid doesn't "hurt" your score; it just makes it move slower. If you beat a Grandmaster in a 10-minute game, you will gain rating points—just fewer points than if you beat them in a 2-hour game.

Summary: GPX vs. ELO

Final Parent Advice: Obsess over the Rating (ELO) for long-term progress, but obsess over the GPX if you are chasing "South African Colours" or invitation to the Closed Championship. They are two different games played on the same board!