Arbitrage & Hedge Bet Calculator

You are exploiting two books that price the same event differently enough that the sum of their implied probabilities drops below 100%. That gap is the only thing you are chasing. No prediction required - you are locking math, not a winner.

Opportunities appear most often during line moves after injury news, during live betting lag, or when a regional book holds different pricing than sharp markets. They rarely last more than a few minutes once both sides are posted.

Do not confuse arbitrage with hedging an existing position. Simultaneous arb means both bets originate from a current disagreement. Hedging after the fact often costs you because the market has already adjusted and you pay a haircut on the second side.

Convert each set of American odds to a decimal multiplier. Take the reciprocal of each decimal to get implied probability. If both reciprocals sum to less than 1.00, you have an arb. The profit margin is 1 minus that sum.

Fix your stake on Side 1 and let the calculator solve Side 2. The calculation sizes Side 2 so that both winning outcomes pay the same dollar amount. The side with longer odds receives the smaller stake because its payout is larger per dollar risked.

The ROI on most arbs is small - often under 2%. That is realistic. Large ROI usually means stale data, a mismatched market, or a line that has already moved.

Keep both book tabs open before entering anything. Odds move fast, especially in live markets. Confirm the lines are still there after you paste them.

Side 2 Stake is read-only - the calculator solves it from your Side 1 inputs. Once you see Guaranteed Profit and ROI, you have enough to decide whether to proceed.

Say Book A has a moneyline at +130 and Book B has the opposing side at +115. You stake $500 on Side 1 at +130. Decimal odds: 2.30 and 2.15. Reciprocals: 43.5% and 46.5%, summing to 90% - a clear arb window.

Side 2 Stake: ($500 x 2.30) / 2.15 = $1,150 / 2.15 = $535. Total stake: $1,035. Whichever side wins pays $1,150. Guaranteed profit: $115. ROI: 11.1%.

That ROI is unusually large - real-world liquid-market arbs average 1-3%. This example uses wide numbers to make the mechanics clear. Most live opportunities are thinner and require speed rather than precision math.

Partial fills strand one leg exposed. If Book A limits you to $200 when you committed $500, your Side 2 hedge is oversized and you carry directional risk. Always confirm bet acceptance at full size before confirming the other side.

Pushes break naive two-way math. Spreads and totals in NFL, NHL, and MLB routinely push on key numbers. If one leg pushes and gets refunded, you are left with a naked bet on the other side at current prices. Rerun the math after any refund.

Soccer and markets with a draw require three-way arb math. You must cover all three outcomes and all three implied probabilities must sum below 100% together. Books price draws specifically to close this gap.