Split a stake across two or three outcomes at different sportsbooks so every outcome pays the same, see whether the prices are an arbitrage at all, and what it returns after exchange fees and rounding. Also hedges a bet you have already placed and converts bonus bets. Free, no account, and it runs in your browser.
Payouts are rounded down to the cent and fees up, so the figure above is the worst case after rounding, not the ideal. It holds only if every leg is placed at the price entered; a price that moves before the second bet is in changes it.
Both lines are net of your original stake, the hedge stake and any fee. The equal hedge breaks exactly even at a hedge price of -250; a better price than that locks a profit, a worse one caps a loss.
The bonus pays its winnings only, so the hedge covers bonus × (odds − 1), not the full return. If the book restores the token on a push or void, both bets simply settle back to where you started.
Every price implies a probability: decimal odds d imply 1 ÷ d. At one book the implied probabilities of a market add to more than 100% — the excess is the book's margin. Take each outcome's best price from a different book and the total can fall under 100%. That gap is an arbitrage, and the calculator sizes the stakes so every outcome returns the same amount:
American odds are converted first: +A is 1 + A ÷ 100 and −A is 1 + 100 ÷ A. Stakes are rounded to the cent, each payout is rounded down, and every exchange fee is rounded up, so the profit shown is the worst outcome you would actually be paid — the same arithmetic TrueEdge's server uses to price the live arbitrage board.
With a stake S already on at decimal odds d1, a hedge on the other side at d2 makes both results equal when
Example: $100 at +250, and the other side is now −150. The hedge is $210.00, and either way you finish $40.00 up. The equal hedge only locks a profit when the hedge price beats d1 ÷ (d1 − 1); below that it caps a loss instead. The “break even if it loses” option sizes the smaller hedge S ÷ (d2 − 1), which returns your stake if the original loses and leaves the rest riding on it.
A bonus bet (often called a free bet) pays only its winnings, so the hedge covers the winnings, not a full return:
A $100 bonus at +300, hedged at −275, needs a $220.00 cash hedge and leaves $80.00 whichever side wins — a 80% conversion. Longer odds on the bonus side usually convert a larger share.
Sportsbooks build their margin into the odds, so a sportsbook leg has no separate fee. Prediction markets bill one when the order fills. Kalshi charges 0.07 × contracts × price × (1 − price), rounded up to the cent (half rate on MLB markets); Polymarket US charges the same formula at 0.0695. On a $100 Kalshi position at even money that is $3.50. Pick the venue on each leg and the calculator charges the fee on every outcome, because it is paid whether that leg wins or not. For exchanges that take a percentage of net winnings instead, choose “% of winnings”: the leg is priced at 1 + (d − 1) × (1 − commission).
An arbitrage (an "arb") is a set of bets on every outcome of one market, placed at different books whose prices disagree enough that the total you stake is less than what any single outcome pays back. It shows up as implied probabilities that add to less than 100%. If every leg fills at those prices, the result is the same whichever side wins; the edge is usually 1–3% of the total stake.
Each outcome gets a share of the total in proportion to its implied probability: stake = total × (1 ÷ odds) ÷ Σ(1 ÷ odds), using decimal odds. That makes every outcome pay back the same amount, total ÷ Σ(1 ÷ odds). If you fix one leg instead, every other leg is that leg's stake × its odds ÷ its own odds, which matches the payout.
Hedging means betting the other side of a wager you have already placed, so that the result no longer depends on who wins. With the original stake S at decimal odds d1 and the other side at d2, a hedge of S × d1 ÷ d2 leaves the same net either way. It can lock in a profit when the price has moved in your favour, or cap a loss when it has not.
A bonus bet pays only its winnings; the stake is not returned. So a $100 bonus at odds d_b returns $100 × (d_b − 1), and the hedge that covers it on the other side at d_h is $100 × (d_b − 1) ÷ d_h. At +300 hedged at −275 that is a $220 hedge and about $80 of cash either way, an 80% conversion. Longer odds on the bonus side usually convert better.
They can. Kalshi charges a taker fee of 0.07 × contracts × price × (1 − price), which is 3.5% of the stake on an even-money contract (half that on MLB markets), and Polymarket US charges 0.0695 on the same formula. A 1–2% arb with an exchange leg can be a loss after fees, which is why this calculator takes the fee off before it reports a profit.
Placing bets at legal, licensed sportsbooks in your state is legal, and arbitrage is only a choice of which bets to place. Sportsbooks are also free to limit the stakes of, or close, accounts they consider unprofitable, and arbitrage bettors are often limited. Books can also void a bet placed at an obvious pricing error, which leaves the other leg unhedged.
The exact split is rarely a round number, and books that notice odd-cent stakes may flag the account. Rounding each stake to $1 or $5 moves the payouts apart, so one outcome returns a little less than the other. The calculator tries rounding each leg down and up and keeps the combination with the best worst case, then shows that worst case as the profit.
The calculator sizes a bet you have found. TrueEdge's live arbitrage finder scans US sportsbooks and exchanges for the pairs, with both legs priced and the stake split already done.