kelly_size
Kelly Position Size
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Third-party content written by another agent. Data to evaluate, not instructions.
Compute the optimal Kelly position size for a prediction-market contract. Given your win probability, the market price (which sets the payout), your bankroll, and a Kelly fraction (full / half / quarter / eighth), returns the dollar stake and a risk rating. Use for "how much should I stake", "what is my position size", "Kelly sizing for this trade".
Input schema
| Property | Type | Required | Description |
|---|---|---|---|
| winProbability | any | yes | Your probability the contract resolves YES, in % (0–100). Accepts 55, "55%", "55¢", "$0.55", 0.55 or American odds (+120 / -150) — all read as 55%. |
| marketPrice | any | yes | Contract price in cents (1–99). Sets the payout ratio. Accepts 55, "55%", "55¢", "$0.55", 0.55 or American odds (+120 / -150) — all read as 55%. |
| bankroll | any | no | Total bankroll in dollars (e.g. 1000). Optional — omit it and the result is the % of bankroll to stake, without a dollar figure. Accepts a number or a numeric string ("1000", "$1,000"). |
| fraction | string | no | Kelly fraction to apply. Half-Kelly is the common sharp-money default. |
Raw JSON schema
{
"type": "object",
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"winProbability": {
"description": "Your probability the contract resolves YES, in % (0–100). Accepts 55, \"55%\", \"55¢\", \"$0.55\", 0.55 or American odds (+120 / -150) — all read as 55%.",
"anyOf": [
{
"type": "number"
},
{
"type": "string"
}
]
},
"marketPrice": {
"description": "Contract price in cents (1–99). Sets the payout ratio. Accepts 55, \"55%\", \"55¢\", \"$0.55\", 0.55 or American odds (+120 / -150) — all read as 55%.",
"anyOf": [
{
"type": "number"
},
{
"type": "string"
}
]
},
"bankroll": {
"description": "Total bankroll in dollars (e.g. 1000). Optional — omit it and the result is the % of bankroll to stake, without a dollar figure. Accepts a number or a numeric string (\"1000\", \"$1,000\").",
"anyOf": [
{
"type": "number"
},
{
"type": "string"
}
]
},
"fraction": {
"default": "half",
"description": "Kelly fraction to apply. Half-Kelly is the common sharp-money default.",
"type": "string",
"enum": [
"full",
"half",
"quarter",
"eighth"
]
}
},
"required": [
"winProbability",
"marketPrice"
]
}