Polymarket Profit Calculator
Estimate payout, selected fees, net profit, expected ROI, break-even probability, and Kelly position size before placing a trade.
Amount spent on shares, before selected entry fees.
Separate portfolio value used only for position sizing.
Your own probability estimate, not a claim about the final outcome.
Uses Polymarket's category fee formula. The individual market is authoritative.
Estimates use the selected protocol category and optional Polyfollow copied taker-entry fee. They exclude slippage, rebates, taxes, bridge or intermediary charges, and any later exit order. The fee displayed on an individual market is authoritative.
Understanding the Metrics
Profit and Payout Formula
Shares equal trade amount divided by share price. Each winning share pays $1.00 at resolution. Net profit subtracts the trade amount and selected entry fees from that gross payout.
Expected ROI
Expected profit equals your estimated probability multiplied by gross payout, minus the trade amount and selected entry fees. Expected ROI divides that estimate by the total amount at risk.
Kelly Criterion
Kelly estimates position size from your probability estimate, the fee-adjusted payoff, and the separate bankroll you enter. Half Kelly uses 50% of the full formula to reduce volatility. Learn more in our copytrading guide.
Break-Even Win Rate
The minimum accuracy needed for gross payout to cover the trade amount and selected entry fees. Without fees it equals the share price. Read the fees guide for more detail on possible trading costs.
ROI Calculator FAQ
How do I calculate profit and payout on Polymarket?
Enter your trade amount, share price, estimated probability, and bankroll. The calculator estimates shares, gross payout, selected entry fees, net profit, expected ROI, break-even probability, and Kelly position size.
What is expected ROI on Polymarket?
Expected ROI estimates the average return on the total amount at risk if you could repeat a trade with the same price and probability estimate many times. This calculator subtracts the selected entry fees before showing expected profit and ROI.
How does the Polyfollow builder fee affect the result?
When enabled, the calculator includes Polyfollow’s 0.5% builder fee for a copied taker entry. Maker orders do not incur the Polyfollow builder fee. An early copied exit may create another taker fee, so this page does not treat the entry estimate as a complete trade lifecycle cost.
What is the Kelly Criterion and should I use it?
The Kelly Criterion estimates the fraction of a separate bankroll to risk based on your probability estimate and the fee-adjusted payoff. Full Kelly can produce large drawdowns. Half Kelly is a more conservative reference, but neither is a guarantee or personalized financial advice.
What does break-even win rate mean?
Break-even probability is the minimum accuracy needed for the gross payout to cover the trade amount and selected entry fees. Without fees it equals the share price. Selected fees raise the threshold.
Does this calculator include every Polymarket fee?
No. The calculator can estimate the current category-based protocol taker fee and the optional Polyfollow copied taker-entry fee. It does not include slippage, rebates, taxes, bridge or intermediary charges, or a later exit order. The fee shown on the individual market remains authoritative.
What happens if the position loses?
A losing share resolves to $0, so the trade amount and applicable entry fees are at risk. Use the outputs as planning estimates, not as a promise of profit.
Compare Traders Before You Copy
Review live trader histories, drawdowns, positions, and market focus before deciding whether a strategy fits your risk tolerance. Past performance does not guarantee future results.