How much should you bet? Enter the market price and what you think the real probability is. EdgeSizer shows your edge, expected value and the Kelly stake for Polymarket, Kalshi or any binary market. Everything runs in your browser.
Buy YES on one market and NO on another (or both on the same market). If the two prices add up to less than $1, the profit is locked in whichever way it resolves.
EdgeSizer is free, with no ads and no tracking. If it saved you from over-betting, you can tip in USDC or ETH on Base, Polygon, Arbitrum or Ethereum. Pay what you want: $5 keeps the tool going.
It's a formula for the share of your bankroll that grows it fastest over the long run, given your edge. For a binary contract priced at p that you believe wins with probability q, full Kelly stakes (q − p) / (1 − p) of your bankroll on YES.
Your probability estimates are never exact. Betting a fraction of Kelly gives up a little growth in exchange for much smaller drawdowns, which is why most professional bettors do it.
Yes. Any yes/no market priced between 0 and 100 works. For sportsbooks, turn the odds into an implied price with the converter first.
No. It's a math tool, and markets carry risk. Only bet what you can afford to lose, and follow the rules where you live.