Chess Rating Performance Calculator
Uses a commonly cited simplified USCF-style K-factor convention -- the official US Chess system uses a more complex dynamic formula, and other federations (FIDE, chess.com) use different K-factors. See FAQ for details.
Enter your rating, your opponent's rating, the result, and your K-factor tier to see exactly how your chess rating changes -- using the standard Elo formula, not a vague estimate.
How it works
- Enter your current rating and your opponent's rating
- Pick the result: win, draw, or loss
- Pick your K-factor tier (new/provisional, established under 2100, or established 2100+)
- See your expected score, rating change, and new rating
Frequently asked questions
What formula does this use?
The standard Elo rating formula: expected score E = 1 / (1 + 10^((opponent rating - your rating) / 400)), and new rating = old rating + K x (actual score - E), where actual score is 1 for a win, 0.5 for a draw, 0 for a loss.
What K-factor should I use?
This tool uses the commonly cited simplified USCF-style convention: K=32 for new or provisional players (fewer than 26 rated games), K=24 for established players rated under 2100, and K=16 for established players rated 2100 or above. The official US Chess system actually uses a more complex dynamic formula, and other federations (FIDE, chess.com) use different K-factors -- pick whichever tier is closest to your situation.
Has this been verified against a real example?
Yes. Using the classic worked example from the Elo rating system (player rated 1613 vs. an opponent rated 1609, a win, K=32), this calculator produces a new rating of 1629 -- matching the standard reference calculation exactly.
When is National Chess Day?
National Chess Day falls on the second Saturday of October -- October 10, 2026.
Related tools
From the blog
Update history
- 2026-10-03 Added links to related tools.
- 2026-10-01 Launched: standard Elo formula (expected score + K-factor) for National Chess Day (Oct 10, 2026), verified against the canonical worked example (1613 vs 1609, win, K=32 -> 1629).