Estimate your new chess rating using the Elo formula after a win, loss, or draw against a specific opponent. All calculations run locally in your browser—your inputs never leave your device.
This calculator uses the standard Elo update formula:
Rnew = Rold + K × (S − E),
where S is the actual score (1 = win, 0.5 = draw, 0 = loss) and
E is the expected score based on the rating difference.