What this calculator does
Elo rating change works out how a single result moves a player or team’s Elo rating. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulaexpected = 1 / (1 + 10^((Rb−Ra)/400)); new rating = Ra + K × (score − expected)
The inputs explained
| Field | What to enter |
|---|---|
| Player A rating | A number. Starts at 1500. |
| Opponent rating | A number. Starts at 1500. |
| Result for A | Choose from Win, Draw, Loss. |
| K-factor | A number. Starts at 20. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with player a rating
Every other input is held at the calculator’s starting values while player a rating varies. Select any row to load that scenario into the calculator.