Uncertainty before conclusions

Board Game Win Rate Confidence Calculator

Compare one observed binary win rate with a 95% Wilson score interval and the target band you actually intend to review.

Playtest result

Observed outcome

This is your review rule, not a universal definition of balance.

Why use a Wilson interval?

A raw percentage hides how much evidence produced it. The Wilson score interval remains useful near 0% and 100% and with smaller samples, where a simple symmetric approximation can behave badly.

Read overlap carefully

If the interval overlaps your target band, the sample is compatible with values inside and outside that band. If it sits wholly outside, that is a stronger review signal—but still not proof that one mechanic caused the result.

Keep comparable games together

Do not combine different rules versions, player counts, factions, or teaching conditions just to increase the game count. Use the Seat Advantage Analyzer or Faction Matchup Analyzer when those conditions define the question.