Find the exact stake split between two venues to capture the spread when their prices disagree. Execution risk, fees, and slippage may erode the spread.
An arbitrage bet (a.k.a. "arb" or "sure bet") exists when two venues price the same event such that the implied probability totals less than 100%. By staking proportionally on both sides, you guarantee a profit regardless of outcome.
The formula:
implied_sum = 1/oddsA + 1/oddsB stakeA = total * (1/oddsA) / implied_sum stakeB = total * (1/oddsB) / implied_sum payout = stakeA * oddsA (== stakeB * oddsB) profit = payout − total
Real-world arbs are rare and short-lived. Bookmakers limit accounts that arb consistently. Spread costs, fees, and slow execution can eat the edge.
PolySharks tracks live Polymarket↔Kalshi cross-platform spreads in real time — the calculator above is the math, the engine is the data.
PolySharks.ai is a market-intelligence and analytics platform operated by 8eight8 LLC. The site is provided for informational and educational purposes only — it is not financial, legal, tax, or gambling advice. Past whale performance and historical data carry no guarantee of future outcomes. Trading prediction markets involves substantial risk of loss, including 100% of principal. Users are solely responsible for compliance with the laws of their local jurisdiction — prediction-market access is restricted or prohibited in some US states and countries; verify legality before depositing or trading on Polymarket or Kalshi. PolySharks does not custody funds and is not affiliated with Polymarket Inc. or Kalshi Inc. 18+ only (21+ in some jurisdictions).