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Prediction Market Profit Calculator
Calculate your potential profit, loss, ROI, break-even probability, and platform fees before you trade. Compare costs across Polymarket, Kalshi, and Robinhood instantly.
Same Trade on All Platforms
| Platform | Total Cost | Fees (Win) | Profit (Win) | Loss (Lose) | ROI (Win) | Break-Even |
|---|
How the Calculator Works
Prediction markets use binary contracts that pay out $1.00 if the event happens and $0.00 if it doesn't. The share price reflects the market's implied probability of the event occurring.
The Math Behind the Calculator
- Total Cost = Buy Price × Number of Shares
- Gross Profit (Win) = ($1.00 − Buy Price) × Shares
- Net Profit (Win) = Gross Profit − Platform Fees
- Loss (Lose) = Total Cost (you lose your entire investment)
- ROI = Net Profit / Total Cost × 100
- Break-Even Probability = Total Cost / (Payout − Fees)
Platform Fee Structures
| Platform | Fee Model | Fee on Wins | Fee on Losses |
|---|---|---|---|
| Polymarket | Taker fee on trade execution | ~0.01% of trade value | ~0.01% of trade value |
| Kalshi | Fee on net profit from winning trades | 7% of net profit (capped at $0.07/contract) | $0 (no fee on losses) |
| Robinhood | Zero explicit fees, wider spreads | $0 explicit fees | $0 explicit fees |
Note on Kalshi fees: Kalshi charges 7% on net profit from winning trades, capped at 7 cents per contract. For a 45-cent buy, the max fee is 7 cents. Kalshi charges nothing on losing trades.
Note on Robinhood: Robinhood charges no explicit prediction market fees, but typically has wider bid-ask spreads than Polymarket. The calculator shows explicit fees only — actual costs may be higher due to spreads on all platforms.
Example Trades
Example 1: Buying Yes at 35¢
You believe an event has a higher chance than 35% of happening. You buy 200 Yes shares at $0.35 each on Polymarket.
- Total cost: $70.00
- If you win: 200 × $1.00 = $200 payout, net profit ~$129.99
- If you lose: You lose $70.00
- ROI if you win: ~185.7%
- Break-even: The event needs to happen more than ~35% of the time for this to be +EV
Example 2: Buying No at 25¢ on Kalshi
The market shows 75¢ for Yes. You disagree and buy 500 No shares at $0.25 each on Kalshi.
- Total cost: $125.00
- If the event does NOT happen (you win): 500 × $1.00 = $500 payout, minus Kalshi fee of $26.25 (7% of $375 profit), net profit = $348.75
- If the event happens (you lose): You lose $125.00, no Kalshi fee
- ROI if you win: ~279%
Frequently Asked Questions
How do you calculate profit on a prediction market trade?
Each share pays $1 if the event happens (Yes) or doesn't happen (No). Profit = (payout per share − buy price) × number of shares − fees. If you buy 100 Yes shares at 40 cents, your cost is $40. If the event occurs, you get $100 back, for a gross profit of $60 minus any platform fees.
What is the break-even probability?
Break-even probability is the minimum likelihood an event must have for your bet to be profitable in expectation. If the true probability is higher than your break-even, you have positive expected value (+EV). It accounts for the buy price plus any platform fees.
How do fees differ between Polymarket, Kalshi, and Robinhood?
Polymarket charges ~0.01% on trade execution (both wins and losses). Kalshi charges 7% on net profit from winning trades only (capped at 7¢/contract), with zero fee on losing trades. Robinhood charges no explicit fees but may have wider spreads. This calculator shows explicit fees; real costs include spreads.
What is the maximum I can lose on a prediction market trade?
Your maximum loss is your total cost (shares × buy price) plus any upfront fees. Prediction markets have bounded downside — unlike leveraged trading, you cannot lose more than you invest. If you buy 100 shares at 35 cents, your worst case is losing $35.
Should I buy Yes or No shares?
Buy Yes if you think the event is more likely than the price implies. Buy No if you think it's less likely. Buying No at 30¢ is economically similar to selling Yes at 70¢. Look at which side has better liquidity and a tighter spread for the best execution.
Can I use this calculator for any event type?
Yes. This calculator works for all binary (Yes/No) prediction market contracts: elections, sports, crypto prices, economic indicators, weather, and more. As long as the contract pays $1 for the correct outcome and $0 for the incorrect outcome, the math is the same.
How is ROI calculated for prediction markets?
ROI = (Net Profit / Total Cost) × 100%. For example, buying at 25 cents and winning nets you 75 cents per share (minus fees). On a $25 investment (100 shares), that's roughly $75 profit, or about 300% ROI. Losing gives you -100% ROI (total loss of investment).
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