Expected Value Studio
Enter multiple outcomes with their probabilities and values. Get EV, variance, and a tornado chart that ranks which assumption matters most. Built to answer "is this bet worth it?" honestly.
Outcomes
Enter each outcome as probability,value (one per line).
Expected value
Tornado sensitivity
Each bar shows how much the EV changes if that one probability is wrong by ±10 percentage points.
What makes this different
Most "EV calculator" pages compute a single number and stop. The interesting question is usually: which assumption, if wrong, would change my decision? The tornado chart ranks outcomes by sensitivity — the longer the bar, the more dangerous that assumption is. A bet with $10,000 EV upside and $50 EV downside might be dominated by the probability of the upside; if you're not confident in that probability, the bet isn't worth it.
Who uses it
- Decision analysts doing decision-tree reviews.
- Investors modeling position-size tradeoffs.
- Gamblers understanding variance as well as expectation.
Limitations
- Probabilities must sum to 1 (or close to it). The tool warns if not.
- EV ignores risk preference. A 1% chance of losing your house has negative EV but positive utility for some risk-seekers — and vice versa.
- No utility-curve modeling. For that, see Kelly Criterion.