Prediction Markets Calculator
How To Use This Prediction Market Calculator
Convert Kalshi, Polymarket, or PredictIt contract prices to traditional betting odds, calculate your payout after platform fees, and see the effective odds you are actually getting.
Choose Kalshi, Polymarket, PredictIt, or Custom. Fee settings are applied automatically.
Input the share or contract price in cents (e.g., 65 for a 65¢ contract).
Enter how many contracts or shares you plan to buy.
See your true odds after fees and compare to sportsbook lines.
How Prediction Market Pricing Works
Prediction markets trade binary contracts priced between 0¢ and 99¢. Each contract pays out $1.00 if the event occurs and $0.00 if it does not.
The contract price directly represents the market's implied probability. A contract at 65¢ implies a 65% chance of the event happening, which is equivalent to -186 in traditional odds.
Decimal Odds = $1.00 / Contract PriceKalshi Fee Calculator & Odds Converter
Kalshi is a CFTC-regulated prediction market where you trade event contracts on politics, economics, weather, sports, and more. Kalshi charges a trading fee using a parabolic formula that varies based on contract price — fees are highest at 50¢ and decrease toward 0¢ and 99¢.
Taker: fee = ceil(0.07 × contracts × P × (1 − P))Maker: fee = ceil(0.0175 × contracts × P × (1 − P))Select “Kalshi” from the platform presets above and choose Taker or Maker to calculate your exact Kalshi fee and payout. Source: Kalshi Fee Schedule (PDF) · Kalshi Help Center
Polymarket Odds Calculator & Payout Calculator
Polymarket is a decentralized prediction market on Polygon where you buy shares priced between 0¢ and 99¢. Polymarket has no explicit trading fees — costs are embedded in the bid-ask spread. This means the share price you pay is very close to your true effective odds.
Select “Polymarket” from the platform presets above to convert any Polymarket share price to traditional odds. Source: Polymarket Docs · Polymarket Fee Structure
PredictIt Fee Calculator & Payout Calculator
PredictIt charges a 10% fee on profits and a 5% fee on withdrawals. These fees compound to significantly reduce your effective returns compared to Kalshi or Polymarket. Always calculate your PredictIt payout after fees before placing a trade.
Select “PredictIt” from the platform presets above. The 10% profit fee is applied automatically. Source: PredictIt — How It Works · PredictIt Fee Schedule
Kalshi vs Polymarket vs PredictIt: Fee Comparison
Fee structures vary significantly across prediction market platforms. This affects your effective odds and payout. Below shows the impact on 100 contracts at 40¢.
| Platform | Fee Model | Fee on 40¢ × 100 | Effective Odds |
|---|---|---|---|
| Kalshi (taker) | 0.07 × C × P × (1−P) | $1.68 (added to cost) | +140 |
| Polymarket | No explicit fee | $0.00 | +150 |
| PredictIt | 10% on profit | $6.00 (from payout) | +135 |
Common Mistakes to Avoid
A 40¢ contract looks like +150 odds, but Kalshi's taker fee drops it to +140, and PredictIt's 10% profit fee drops it to +135. Always use effective odds when comparing to sportsbook lines.
The contract price is per contract. Your total cost is the price multiplied by the number of contracts. Buying 200 contracts at 40¢ costs $80, not 40¢.
The displayed contract price may differ from the actual price you pay due to the bid-ask spread. Illiquid markets have wider spreads that increase your effective cost.
You do not have to hold contracts until settlement. If the price moves in your favor, you can sell for a profit before the event occurs. Fees may also apply to early exits.
Frequently Asked Questions
How do I convert Kalshi contract prices to American odds?
First convert to decimal: Decimal Odds = $1.00 / price. A Kalshi contract at 40¢ = 1/0.40 = 2.50 decimal = +150 American. For contracts above 50¢, you get negative American odds: 65¢ = 1.538 decimal = -186 American. Select Kalshi above and the calculator handles it automatically.
How do I calculate my Polymarket payout?
Multiply the number of shares by $1.00 to get your gross payout if the event occurs. Subtract your total cost (shares × share price) to get profit. Since Polymarket charges no explicit fees, your gross payout equals your net payout. Select Polymarket above for automatic calculations.
How much does PredictIt charge in fees?
PredictIt charges 10% on all profits from winning contracts. They also charge a 5% withdrawal fee on funds you withdraw from the platform. On a 40¢ contract that wins, the 60¢ gross profit loses 6¢ to fees, giving you 54¢ net profit per contract. Select PredictIt above for exact calculations.
How do Kalshi fees work?
Kalshi uses a parabolic fee formula: ceil(coefficient × contracts × P × (1−P)) where P is the contract price. Takers pay a 7% coefficient (max 1.75¢/contract at 50¢), makers pay 1.75%. The fee is added to your cost — you still receive the full $1.00 payout per winning contract. Fees are lowest near 0¢ and 99¢, making tail trading cheaper.
Can I compare Kalshi odds to sportsbook odds?
Yes. Use this calculator to convert any Kalshi contract price to American or decimal odds, then compare to sportsbook lines on the same event. Make sure to select Taker or Maker to see effective odds after Kalshi's trading fee — especially at mid-range prices where the fee is highest.
Can I buy “No” contracts on Kalshi and Polymarket?
Yes. Both Kalshi and Polymarket let you buy “No” contracts (or sell “Yes” shares) that profit if the event does not occur. A “Yes” contract at 65¢ is equivalent to a “No” at 35¢. Just enter the “No” price in this calculator to see your odds and payout.
Which prediction market has the lowest fees?
Polymarket has no explicit trading fees. Kalshi's parabolic fee is small (max 1.75¢/contract for takers at 50¢, even less for makers and at extreme prices). PredictIt is the most expensive at 10% on profits plus 5% on withdrawals. Use this calculator to compare effective odds across platforms.
Can I use this for crypto prediction markets like Polymarket?
Yes. Polymarket is a crypto-based prediction market but the math is identical — shares trade between 0¢ and 99¢ and pay $1.00 on a correct prediction. Select Polymarket from the presets and the calculator handles everything. It also works with other crypto prediction markets via the Custom option.
Pro Tip: Compare Kalshi & Polymarket Odds to Sportsbooks
Prediction markets like Kalshi and Polymarket often have different odds than sportsbooks on the same events. Polymarket has no explicit fees, making direct comparison easy. Kalshi's taker fee is small but still shifts the odds — a 40¢ contract (+150) becomes +140 after fees. On PredictIt, the 10% profit fee is more significant — that same 40¢ contract drops to +135. Always use this calculator to compare effective odds across all platforms.