API reference

Single-bet Kelly

The Kelly stake for each bet, sized on its own. No daily limit.

POST/v1/kelly

Each bet is sized alone: no per-bet cap, no limit on the total, and no allowance for bets that win or lose together. For bets you will place on the same day, optimize applies all three and usually allocates less.

Request

Field	Type	Required	Meaning
`bets`	array	yes	1 to 100 bets.
`bets[].odds`	integer	yes	American odds.
`bets[].probability`	number	yes	Your win probability, 0.000001 to 0.999999.
`bets[].id`	string	no	Your own label, echoed back.
`bankroll`	number	no	USD. Send it to get `stake` in dollars.
`fraction`	number	no	Kelly multiplier, above 0 and at most 1. Default 1; `0.5` is half Kelly.

Example

An even-money bet you think wins 55% of the time, at half Kelly:

curl https://api.kellyiq.com/v1/kelly \
  -H "Authorization: Bearer $KELLYIQ_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "bets": [
    { "id": "a", "odds": 100, "probability": 0.55 }
  ],
  "bankroll": 1000,
  "fraction": 0.5
}'

{
  "fraction": 0.5,
  "bankroll": 1000,
  "results": [
    {
      "id": "a",
      "odds": 100,
      "probability": 0.55,
      "decimalOdds": 2,
      "breakEvenProbability": 0.5,
      "expectedValue": 0.1,
      "kellyFraction": 0.1,
      "stakeFraction": 0.05,
      "stake": 50
    }
  ]
}

Response

The request’s fraction and bankroll are echoed back, then one result per bet, in your order:

id, odds, probability: your input, echoed. decimalOdds: total return per 1 staked.
breakEvenProbability: the win rate at which the bet makes nothing.
expectedValue: expected profit per 1 staked.
kellyFraction: full Kelly. Negative means no edge.
stakeFraction: the share of the bankroll to stake: the larger of 0 and kellyFraction, times fraction.
stake: that in dollars; null when no bankroll was sent.

Errors

Every problem in the request is reported at once:

{
  "error": "VALIDATION_ERROR",
  "message": "The request is invalid; see violations.",
  "violations": [
    "bets[0].odds: American odds: at most -100 or at least +100 (magnitude ≤ 100000)",
    "bets[0].probability: required, between 0.000001 and 0.999999",
    "bankroll: must be greater than 0 and at most 100000000"
  ],
  "requestId": "req_24751790ee084a49a0ae4deb82000e53"
}

Also 429 BURST_LIMIT_EXCEEDED above 60 calculator calls a minute. See Errors.

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