See what prediction markets are actually charging you.
Free tools for EV, break-even price, position sizing, vig, parlays, and tax. Built for Kalshi, Polymarket, and PredictIt.
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Understand the Price
Enter any contract price. See implied probability, American odds, decimal, and fractional — all at once. Plus payout, fees, and profit in plain English.
Open tool →Measure the Opportunity
Enter the market price, your probability estimate, and see fee-adjusted expected value, break-even win rate, and a clear verdict on whether the trade is favorable.
Open tool →Manage Your Risk
Found an edge? See ¼, ½, and full Kelly sizing — adjusted for platform fees — with break-even analysis and a sensitivity table.
Open tool →All Calculators
Fees Calc
Side-by-side net cost after all fees — Kalshi vs Polymarket vs PredictIt.
Open tool →Tax Estimator
Estimate what you keep after federal tax under three IRS approaches.
Open tool →No-Vig Calculator
Enter YES and NO prices. See the overround, fair odds, and what the market is really charging per side.
Open tool →Parlay Calculator
See how vig compounds across legs — not just the headline payout.
Open tool →Implied Probability
Strip the vig from any two-outcome or multi-outcome market to find fair probability.
Open tool →Guides & Articles
How to Place Your First Prediction Market Trade
A step-by-step walkthrough for new Kalshi users
Read article →GuideWhat Is Kalshi?
How it works, what it costs, and whether it's legit
Read article →GuideWhat Is an Event Contract?
How binary contracts work, how they pay out, and how they differ from traditional bets
Read article →ComparisonKalshi vs Polymarket
Side-by-side fee math and honest comparison (2026)
Read article →ReviewIs Kalshi Legit?
CFTC regulation, the lawsuits, fees, and honest weaknesses
Read article →Fee GuidePrediction Market Fees Compared
Exact taker/maker rates for Kalshi, Polymarket, and Robinhood (2026)
Read article →GuidePolymarket Weather Trading
How to trade weather markets on Polymarket — fees, strategy, and edge
Read article →Supporting data and math for Kalshi · Polymarket · PredictIt