Kelly bet stake sizing API

Kelly criterion stake sizing for a single bet from win probability and decimal odds, returning full and fractional-Kelly fractions, recommended stake on a bankroll, edge, and expected log-growth, with a no-bet flag for non-positive edge. Answers 'How much should I stake using Kelly?', 'What is my half-Kelly bet size?'.

Price$0.06per request

MethodPOST

Route/v1/sports/kelly-stake

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

sportsbettingkellystakebankrollmoney-managementfractional-kellyedgebet-sizing

API URLhttps://x402.hexl.dev/v1/sports/kelly-stake

Integration docs

Example request

{
  "winProbability": 0.55,
  "decimalOdds": 2,
  "bankroll": 1000
}

Example response

{
  "winProbability": 0.55,
  "decimalOdds": 2,
  "b": 1,
  "edge": 0.1,
  "fullKellyFraction": 0.1,
  "kellyMultiplier": 1,
  "recommendedFraction": 0.1,
  "recommendedStake": 100,
  "bankroll": 1000,
  "expectedLogGrowthFullKelly": 0.005008,
  "recommendation": "bet",
  "formula": "f* = (b·p - q)/b, b = decimal-1, q = 1-p; stake = f*·multiplier·bankroll"
}

Input schema

{
  "type": "object",
  "required": [
    "winProbability",
    "decimalOdds"
  ],
  "properties": {
    "winProbability": {
      "type": "number",
      "description": "Estimated win probability in (0,1)",
      "examples": [
        0.55
      ]
    },
    "decimalOdds": {
      "type": "number",
      "description": "Decimal odds > 1",
      "examples": [
        2
      ]
    },
    "bankroll": {
      "type": "number",
      "description": "Bankroll to size against",
      "examples": [
        1000
      ]
    },
    "kellyFraction": {
      "type": "number",
      "description": "Kelly multiplier in (0,1], e.g. 0.5 for half-Kelly",
      "examples": [
        1,
        0.5
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}