Updated · Methodology: named formula library
Elo Rating Change Calculator
Calculate Elo rating change from match result (chess, online competitive games).
Expected 36.0% win, K=32. 1500 + 32 × (1 − 0.36) = 1520 (+20.5).
Elo Rating
Used in chess, League of Legends, CS, etc. K-factor: 32 for active players, 16 for masters. Your rating change scales with the gap — beating someone 200 pts higher gains more than beating an equal opponent.
Worked Example
1500 beats 1600 (K=32)
- ownRating
- 1500
- oppRating
- 1600
- result
- 1
- Result
- New rating: 1521 (+21)
Expected win = 36%. Won. ΔR = 32 × (1 − 0.36) = +21.
When to Use This Calculator
- Predict Elo gains/losses
- Estimate matchmaking outcomes
Limitations & Common Mistakes
- Results are estimates based on the inputs you provide.
- Always verify with current data and consult a professional for major decisions.
Frequently Asked Questions
How does Elo work?
Expected = 1 / (1 + 10^((opponent − own) / 400)). New rating = old + K × (actual − expected). Win = 1, Draw = 0.5, Loss = 0. K-factor: 32 for active players, 16 for masters, 10 for top-100. Beating someone 200 points higher = +21 if K=32. Losing to a 200-points-lower opponent = −27.
Why 400?
It's the scale parameter Arpad Elo chose so a 200-point gap = ~75% expected win rate, and a 400-point gap = ~91%. Different games tune this differently; standard chess and most online games use 400.
Is Elo fair?
Asymptotically yes — over many games, Elo converges to your "true" skill level. Short-term it's noisy (single matches can swing your rating ±30 points). Smurfs and rating decay can distort the system; modern games use Glicko or TrueSkill to address volatility.
What's K-factor?
Controls how much a single match changes your rating. Higher K = faster adaptation (good for new players whose true skill is uncertain). Lower K = more stable rating (good for established players). FIDE uses K=40 for new players, K=20 for under-2400, K=10 for elite.
Related Calculators
More Gaming →Game MMR Percentile
Estimate your percentile rank from MMR/SR distribution.
Game Completion Time Calculator
Hours to 100% at your pace.
Target FPS Monitor Hz
Minimum monitor Hz for buttery play.
Mouse eDPI Calculator
Effective DPI = DPI × in-game sens.
cm/360° Aim Sensitivity
cm of mouse travel per 360° turn.
Loot Drop Probability Calculator
Chance of at least one drop in N tries.