Skill Rating From Wins Calculator

How it is calculated

The rating is a base value shifted by the base-10 logarithm of the win-to-loss ratio:

rating = base + 400 × log10(wins ÷ losses)
win rate = wins ÷ (wins + losses) × 100

A record with equal wins and losses sits exactly on the base; each time the ratio multiplies by 10 the rating moves by 400 points. To avoid dividing by zero or taking the log of zero, a count below 0.5 is replaced by 0.5, so 10 wins and no losses is treated like 10 against 0.5. If you leave the base empty, 1000 is used. The tool does not weigh the strength of opponents or recent form: it only looks at the totals, so it is a rough estimate, not an official ladder rating.

Common mistakes

• Expecting a percentage change in the rating. The result is in rating points, where a 1.5 to 1 record adds about 70 points whatever the sample size.
• Trusting a rating from a handful of games. With 1 win and 0 losses the tool shows 1,120, which looks impressive but rests on a single match.
• Mixing up the win rate with the ratio. A 60% win rate is a 1.5 ratio (30 to 20), not 0.6, and the formula uses the ratio of wins to losses, not the share of games.
• Counting draws as wins or losses. Only two numbers are read, so decide beforehand how draws count (for example half a win and half a loss) and enter the totals that way.
• Comparing results made with different base ratings. A base of 1500 and a base of 1000 differ by 500 points for the same record, so only compare ratings with the same base.