How much should you bet? Enter your bankroll, the market price, and what you think the real probability is. Uses the Kelly Criterion — the math behind optimal bet sizing.
The YES price on Polymarket or Kalshi. E.g., 65 means 65¢ = 65% implied probability.
What you think the REAL chance of YES is. Must be higher than the market price for an edge.
Your Edge—
Full Kelly (aggressive)—
Half Kelly (recommended)—
Quarter Kelly (conservative)—
If you win—
If you lose—
How to use: Half Kelly is the standard for most traders. It gives ~75% of the growth rate with half the volatility. Never bet more than 5% of your bankroll on a single market, even if Kelly says to.
No edge? If your probability estimate is at or below the market price, Kelly says don't bet. The market already prices in what you know.