Prediction Market Arbitrage Calculator
Compare the cost of matching YES and NO shares with their $1 combined payout. Calculate fees, net margin, ROI and break-even from your own prices.
What does one of each outcome cost?
Enter executable buy prices for a matching YES and NO pair that together pay $1. Prices and fees are manual inputs; this tool does not find live opportunities.
100 on each side means 100 YES shares plus 100 NO shares. Include costs for both legs; use expected average fill prices to account for slippage. Fees default to an illustrative $2, not a venue schedule.
Net result at matching settlement
$3.00
Positive margin under these assumptions.
- YES purchase cost
- $52.00
- NO purchase cost
- $43.00
- Combined price per pair
- 95.00¢
- Total cost including fees
- $97.00
- Combined settlement payout
- $100.00
- Return on total cost
- 3.09%
- Break-even combined price
- 98.00¢
This estimate assumes both orders fill in full, exactly one outcome pays $1, and the contracts have matching resolution rules. Similar market titles across venues are not enough. Partial fills, disputes, different rules and unavailable liquidity can change or eliminate the result.
How paired-outcome arbitrage works
A matching binary YES and NO share together pay $1 at ordinary settlement: one wins and one loses. Buying both for less than $1 creates a gross margin. The useful comparison is the executable cost of both shares plus fees against that combined payout.
For 100 pairs at 52¢ YES and 43¢ NO, the purchase cost is $95. A $100 paired payout leaves $5 before costs. With $2 in total costs, the scenario returns $3 on $97, or about 3.09%. At 55¢ YES and 47¢ NO, the shares alone cost $102, so there is a loss even before fees.
Formula and break-even
Net result = number of pairs × (1 − YES price − NO price) − total costs. Prices in this formula are dollars: 52¢ is 0.52. Return on cost = net result ÷ total purchase cost including fees.
The break-even combined price is $1 minus costs per pair. With $2 of costs for 100 pairs, the sum of YES and NO prices must be below 98¢ for a positive result. The calculator holds the total costs you enter fixed; update them when order size or quotes change.
What to check before comparing two quotes
Read the settlement source, cutoff time, cancellation treatment and outcome definitions on both contracts. Confirm enough quantity is actually offered at your prices. A last trade, midpoint or indicative chart value is not necessarily available to buy. Capital may stay committed until resolution.
This calculator models equal quantities of two complementary $1 outcomes. It does not scan markets, annualize returns, execute orders, or model multiple-outcome markets. For a one-sided position, use the profit calculator. For quote notation, use the odds converter.
Topic reference: Polycool’s trading strategies guide. This is an independent calculation with manually entered costs.