Table Tennis Rating Calculator
Calculate your new Elo-style rating after a match or tournament using the USATT/ITTF methodology.
About this calculator
This calculator implements the same modified Elo system USATT and ITTF use to update player ratings after competition. Every match starts with an expected win probability, E = 1 / (1 + 10^((opponentRating − yourRating) / 400)) — the standard Elo curve, where a 400-point rating gap implies roughly a 10-to-1 favorite. Your rating then moves by K × (actual result − expected result) for each match, summed across every win (scored 1) and loss (scored 0) in the event, so beating a much higher-rated opponent repeatedly swings your rating far more than the same margin against an evenly-matched player.
The K-factor — how sensitive your rating is to each result — isn't fixed: it's 40 if you're provisional (fewer than 8 rated events, since your rating is still unreliable), 32 below 2100, 24 between 2100 and 2399, and just 16 at 2400+, reflecting that established elite players' true skill should move only gradually. Beyond the raw rating change, the calculator derives a "performance rating" — the rating level your actual results imply, solved by inverting the Elo formula (capped at opponent rating ±400 if you swept or were swept) — and an "upset factor" showing how far your actual win rate diverged from what was statistically expected. One quirk to know: if you enter zero total matches, the calculator returns your rating unchanged with a neutral 50% expected/0% actual split rather than attempting a division by zero, so an empty submission won't distort your numbers.
Inputs
Results
New rating
1,516
Rating change
16
How to Use This Calculator
- Enter Your current rating, Opponent rating, and Matches won.
- Set Matches lost, Provisional rating?, and Total tournament games.
- Review New rating and Rating change.
- Use Expected win % and Actual win % to inform your decision.
How the result changes with Your current rating
| Your current rating | New rating | Rating change |
|---|---|---|
| 750 | 844 | 93.9 |
| 1,125 | 1,204 | 79.4 |
| 2,250 | 2,204 | -46.4 |
| 3,000 | 2,968 | -32 |
What each input means
- Your current rating
- Your current USATT or club Elo rating.
- Opponent rating
- Average rating of your opponent(s).
- Matches won
- Number of matches you won.
- Matches lost
- Number of matches you lost.
- Provisional rating?
- Set to 1 if you have fewer than 8 rated events (higher K-factor).
- Total tournament games
- Total games played in the event (for context).
What each result means
- New rating
- Your estimated rating after this event.
- Rating change
- Points gained or lost. Positive = improvement.
- Expected win %
- Your predicted win probability based on rating difference.
- Actual win %
- Your actual win percentage in this event.
- Performance rating
- The rating level you played at during this event.
- K-factor used
- The K-factor determines how much each game affects your rating.
- Upset factor
- Positive = overperformed expectations, negative = underperformed.
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why is my rating change based on the sum of results across all my matches instead of just my overall win percentage?
The calculator computes a separate expected result for each match based on the single opponent rating you enter, then sums K × (1 − expected) for every win and K × (0 − expected) for every loss to get the total rating change. This means the formula applies the same match-by-match Elo logic the real USATT/ITTF system uses, rather than treating your event as one lump result — it just assumes all your matches were against opponents of the rating you entered.
Why does my K-factor matter, and when would I get 40 instead of 32?
The K-factor scales how much each match result moves your rating — the calculator assigns 40 if you're marked provisional (fewer than 8 rated events, since your true rating is still uncertain), 32 if your rating is below 2100, 24 between 2100 and 2399, and just 16 at 2400 and above. Provisional status overrides the rating-based tiers entirely, so even a very high provisional rating still gets the most volatile K-factor of 40.
What does the 'performance rating' actually represent, and how is it different from my new rating?
Performance rating is the rating level that would make your actual win percentage exactly match the Elo-predicted expected percentage against this opponent — the calculator solves the expected-score formula in reverse to find it, capping at opponent rating plus or minus 400 if you swept or were swept. It's a snapshot of how you played in this specific event, separate from your new rating, which is your prior rating adjusted incrementally by the K-factor rather than reset to match your performance.
What happens if I enter zero total matches?
The calculator detects that matchesWon plus matchesLost equals zero and returns your rating completely unchanged, along with a neutral 50% expected win rate and 0% actual win rate, rather than dividing by zero when computing actualScore. This is a deliberate guard so an empty or incomplete submission doesn't produce a distorted or crashing result.
Does the 'Total tournament games' field affect my rating?
No — it's collected for context only. The rating change is computed entirely from matches won and matches lost, and the total tournament games field doesn't currently feed into any calculated value.
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