Formula
The formula is displayed so the result can be checked independently. PreBreakout does not use a hidden scoring model on this page.
Worked hypothetical example
If a hypothetical sample contains 28 wins and 22 losses, there are 50 decisive outcomes and the observed win rate is 56%. Five additional break-even outcomes would not change that decisive-outcome win rate, but wins would represent 50.91% of all 55 closed outcomes.
Important: the numbers are fictional and are not associated with a security, issuer or current market price.
What this calculator does not tell you
- Winning, losing and break-even counts must be whole numbers and cannot be negative.
- The main win-rate result excludes break-even outcomes from the denominator; the page also reports wins as a share of all closed outcomes so the convention is explicit.
- Observed win rate describes the entered sample only. It does not estimate future probability or show whether average wins exceed average losses.
Observed win rate is not break-even win rate
Observed win rate counts how often wins occurred in the sample you entered. Break-even win rate is a theoretical threshold derived from payoff geometry. A sample can have an observed win rate above or below a theoretical threshold, but comparing the two still does not forecast future results.
Calculate theoretical break-even win rate →
Why break-even outcomes need a stated denominator rule
Different journals handle flat outcomes differently. PreBreakout keeps the convention visible: the primary percentage is wins divided by wins plus losses, while a separate result shows wins divided by all closed outcomes including break-even entries. This avoids silently changing the denominator.
Example calculations
| Wins | Losses | Break-even | Decisive win rate |
|---|---|---|---|
| 6 | 4 | 0 | 60% |
| 28 | 22 | 0 | 56% |
| 28 | 22 | 5 | 56% |
| 0 | 10 | 0 | 0% |
What win rate leaves out
Win rate does not contain payoff size. Two samples with the same win rate can have different expectancy and profit factor if their average wins and losses differ. Use the related calculators to inspect those separate pieces rather than treating win rate as a quality score.
How to use it for learning
Change one input or observation at a time and check how the output changes. The page reports only deterministic arithmetic from your inputs; it does not convert the result into a quality score, forecast or trading instruction.