ELO rating change calculator
Work out your pre-match win probability and expected rating change from two Elo/MMR ratings, a match result and a K-factor.
This is an estimate based on the standard Elo formula — it's not a guarantee, and it may not exactly match a specific game's internal rating system.
The core idea: Elo compares what actually happened to what was expected. Beating a higher-rated opponent moves your rating up more than beating an equal, because that result was the less likely one — an "upset," in Elo terms. The K-factor is what controls how big that swing is; a higher K-factor reacts faster to recent results, a lower one keeps ratings more stable over time.
Tracking your kills instead? Try the K/D & KDA calculator.
Report an issue with this calculationWorked example
Say you're rated 1450, facing an opponent rated 1600, K-factor 32. Expected score ≈ 0.297 — about a 30% chance of winning. If you win anyway: 32 × (1 − 0.297) ≈ +22.5 rating points — a big gain, because beating the favourite was the less-expected outcome.
Compare that to two equally-rated players, both at 1500, K-factor 32. Expected score is exactly 0.5 for each. A win there only gains 32 × (1 − 0.5) = +16 points — half as much, because that result was already the coin-flip expectation.
FAQ
What is the K-factor?
How much a single match can move your rating. A higher K-factor reacts faster to recent results; a lower one is more stable. 32 is a common default for casual/online play — many games use a lower value for established, high-rated players.
Why does beating a higher-rated opponent gain more rating?
Elo compares the actual result to the expected result. Beating a favourite was 'less expected', so it moves your rating up by more than beating an equally-rated opponent would.
Does this match my game's exact MMR system?
Most competitive games use Elo or a close variant (often with hidden per-mode adjustments), so this is a close approximation, not necessarily an exact match to any one game's internal formula.
Is the K-factor a fixed set of options?
No — it's a plain number field, not a dropdown. Enter any value; 32 is a common starting point.
What does the pre-match win probability tell me?
The Elo formula's estimate of how likely you are to win, based purely on the rating difference between you and your opponent — not a forecast that factors in current form, specific matchups, or anything beyond the two numbers entered.
What does a negative rating change mean?
You lost the match — the number shows how much your rating drops as a result.
Can I use this for a draw?
Yes — select "Draw" as the result. Between two equally-rated players a draw produces no change; between unevenly-rated players it still shifts each rating slightly toward the expected outcome.
Does beating a much lower-rated opponent still change my rating?
Yes, just by a small amount — since that win was already expected, the formula only gives you a small positive change rather than a large one.
Can I use this calculator for games other than the one it's shown on?
Yes — the Elo formula isn't specific to any one game. Many competitive games and platforms use it or a close variant, so the same two-rating math applies broadly.
Can I check the win probability before playing the match?
Yes — the win probability only needs the two ratings, so you can check it beforehand. The rating-change figure needs an actual (or hypothetical) result, since it depends on what happened.