📊 Win Probability Calculator
Enter two ratings and see each player's expected chance of winning, computed from the logistic ELO curve that powers table tennis ranking systems.
📊 Expected Win Probability
Probabilities come from the logistic ELO curve: a 400-point edge means about a 91% chance to win. These are long-run expectations across many matches, not a guarantee for any single game.
What is a Win Probability Calculator?
It converts the rating gap between two players into a head-to-head win percentage for each of them. The same logistic curve that ELO uses to set expected scores tells you how often the favourite should win — 64% at a 100-point edge, about 91% at 400 — so you can read a match-up at a glance.
Use it to size up a draw before a tournament, to explain why a seeded player is expected to win but is far from certain, or to set fair expectations for a coaching group. Pair it with the rating and handicap calculators to see both the odds and the points a fair game would need.
❓ Frequently Asked Questions
How do you turn a rating difference into a win probability?
With the logistic ELO curve. The favourite's chance of winning is 1 / (1 + 10^((underdog rating − favourite rating) / 400)). The two players' percentages always add up to 100, because ELO folds the small chance of a draw into the expected score.
What does a 100-point rating gap mean in practice?
About 64% for the higher-rated player. A 200-point gap is roughly 76%, and a 400-point gap is about 91%. The curve is deliberately gentle near even ratings and steep once the gap is large, which matches how table tennis results actually behave.
Are these odds a guarantee for one match?
No. They are long-run expectations across many matches between players of those ratings. On any given day form, style match-ups, and nerves can override the numbers — that is exactly why upsets happen and why the underdog still has a real chance.
Can I use this for any rating system?
Yes, as long as the ratings share the same 400-point scale that USATT, ITTF, and most ELO-based systems use. If your league uses a different spread, the shape of the curve stays the same but the exact percentages will shift.