⚖️ Arbitrage Calculator
Sportsbook on one side, Kalshi on the other. Find out if the prices disagree enough to lock in a risk-free profit — Kalshi taker fees included.
How Kalshi vs. sportsbook arbitrage works
Arbitrage exists when two venues price the same outcome differently enough that you can back both sides and profit no matter what happens. Because Kalshi is a regulated exchange while sportsbooks set their own lines, the two often disagree on the same game. This calculator bets the event to happen at the sportsbook and buys NO on Kalshi to cover the other side, then checks whether the combined position locks in a profit after Kalshi's taker fee.
Enter both prices
Put in the sportsbook's American odds for the event happening, the Kalshi YES price for the same event, and how much you'd stake at the book.
We size the hedge
The calculator works out how many NO contracts to buy on Kalshi so both outcomes return the same amount — true equal-profit arbitrage sizing.
Fees are baked in
Kalshi's taker fee on the NO leg is included, because an 'arb' that ignores fees often isn't one. You see the guaranteed profit and ROI after costs.
Get a clear verdict
Green means a locked-in profit exists at these prices; red means the combined prices still imply more than 100% — no free money, wait for a better line.
Frequently asked questions
Is arbitrage between Kalshi and sportsbooks legal?
Trading the same event on a regulated exchange and a licensed sportsbook is generally permitted, but every operator has its own terms — some books limit or close accounts that arb heavily. This tool is for analysis and education, not legal or financial advice; check each platform's rules and your local laws.
Why does the calculator include Kalshi fees?
Taker fees can erase a thin arbitrage entirely. A 1–2¢ gap might look profitable until the fee on the Kalshi leg eats it. Including fees up front keeps you from firing a 'sure thing' that actually loses money.
Why is there so rarely an arbitrage?
Markets are reasonably efficient, and the combined prices usually imply slightly more than 100% once vig and fees are counted. Real arbs are brief and small. The more practical use is finding +EV edges (one side mispriced), which our EV calculator and Edge Scanner handle.
What can break an arbitrage after I place it?
Settlement differences are the big risk: the sportsbook and Kalshi must settle on identical terms (overtime rules, pushes, postponements). If the two define the outcome differently, your 'risk-free' position can lose. Always read both rulebooks before firing.