Tool
AvailableEdge calculator
Verification presets
Probability of a negative outcome
1.822×10^-66 %
Normal approximation, for reference: 5.119×10^-64 %
Negative outcome with at most 249 wins
Exact binomial calculation
Expectancy per trade
1.08 R
Expected total
1080.00 R
Kelly criterion f*
36.00 %
The same probability in expanded form
0.000000000000000000000000000000000000000000000000000000000000000001822 %
Putting the number in context
NASA considers no known asteroid a significant impact risk over the next 100 years. These probabilities come from different models and are not compared numerically.
NASA sourceWhat the model does not include
- Trades are assumed independent, although real outcomes cluster by market regime.
- Win rate and R are assumed constant; even a 1–2 pp estimation error changes the tail sharply.
- A trade has only two outcomes, +R or −1R; gaps, partial exits, and slippage are excluded.
- Fees are excluded, and only the final sum is modeled, not drawdown along the path.
- Additive R units are not percentages of capital; Kelly is growth-optimal, not a safe position size.
- An extremely small number is exact only within the model; input-estimation error matters more than dozens of result digits.
Educational model. Not individualized investment advice.
What the calculator measures
The calculator finds the probability of ending exactly N trades with a negative sum in R, given a fixed win rate and reward-to-risk ratio.
This is not risk of ruin, path drawdown probability, or a forecast of account returns.
Learn more
Formulas on this page
- The strict event is S_N < 0, not S_N ≤ 0.
- The exact binomial tail is computed in log space.
- Expectancy is shown per trade and for the full horizon.
- Kelly is shown separately and is not trading advice.