ROI Calculator
Calculate expected ROI, optimal position size with Kelly Criterion, and break-even win rates for your Polymarket trades.
Example: Market says 60%, you think it's 65% → your edge is +5%
Understanding the Metrics
Expected ROI
Average return you'd expect if you made this trade many times. Positive = profitable edge, negative = losing proposition. Formula: (Your Prob × Win) - (1 - Your Prob)
Kelly Criterion
Optimal position size to maximize long-term growth while minimizing risk of ruin. Many traders use "half Kelly" (50% of suggested) to reduce volatility.
Break-Even Win Rate
Minimum accuracy needed to not lose money at this price. If the market is at 60%, you need >60% accuracy to profit. Your edge should push you above this threshold.
Ready to Trade with an Edge?
Copy traders who consistently find positive expected value opportunities. Use their edge instead of searching for your own.