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Expected Value & Probability Calculator
x402
Expected Value & Probability Calculator is a paid API for AI agents from probability-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Computes expected value, variance, standard deviation, and probability of profit for a discrete set of payoff/probability pairs.
Price / call$0.02
Success—
StatusUnknown
How this service works
Expected value, variance, standard deviation and chance of profit for a list of payoffs with probabilities or weights.
Output
Returns a JSON object containing: expected value, variance, standard deviation, probability of a positive outcome (profit), probability of a loss, best and worst outcomes with their probabilities, break-even cost, the normalized list of outcomes, and optionally a summary and disclaimer. Also includes the cost applied if a cost parameter was supplied.
Example use cases
Evaluating a lottery ticket purchase
“I'm thinking about buying a $2 scratch ticket. There's a 1-in-10 chance of winning $5, a 1-in-50 chance of winning $20, and a 1-in-1000 chance of winning $500. The rest is a loss. Can you calculate the expected value and probability of coming out ahead, subtracting the $2 cost?”
Analyzing a venture investment payoff
“I have an investment with three outcomes: 40% chance of a $0 payoff (total loss), 45% chance of a $50k return, and 15% chance of a $300k return. What's the expected value, variance, and standard deviation of this investment?”
Comparing weighted scenario outcomes
“I have four business scenarios with relative likelihoods of 3, 5, 7, and 2 — and payoffs of -10000, 5000, 20000, and 50000 dollars respectively. Please normalize those weights to probabilities and tell me the expected value, standard deviation, and probability of profit.”
Technical details
Endpoint
GEThttps://probability-calc.x402tookit.com/expected-value?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to evaluate a discrete probability distribution with explicit payoffs and probabilities or weights — such as a gamble, investment scenario, insurance payout, or any decision tree leaf. It is ideal when you already know the probability or weight for each outcome and want a full statistical summary including EV, variance, standard deviation, and win/loss probabilities. Prefer it over spreadsheet computation when you want a structured, machine-readable result that includes derived metrics like break-even cost and best/worst outcomes in one API call.
Side effects
- Missing or malformed outcomes query parameter returns an error
- Probabilities that don't sum to 1 without normalize=true may produce misleading results
- Non-numeric payoff or probability values cause a parse failure
- Empty outcomes list returns an error or undefined statistics
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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