Arbitrage betting is backing every outcome of one game at different sportsbooks, at prices that return more than the total staked whichever side wins. It exists only when the implied chances of the best price on each side add up to less than 100%.
That condition is uncommon. We took the best moneyline on each side, from up to 11 sportsbooks, for the 14 NFL Week 6 games on October 13, 2026. No game met it, and the closest pair added up to 100.69%.
The formula: two implied chances under 100%
A price’s implied chance is 1 divided by its decimal odds. In American odds, -110 implies 110 / 210 = 52.38% and +135 implies 100 / 235 = 42.55%. Our guide to how betting odds work has every conversion.
One sportsbook’s two prices on a game add up to more than 100%, and the excess is its margin. At -110 on both sides the sum is 104.76%. In our Week 6 read, the two sides at a single book added up to between 103.01% and 106.19%.
An arbitrage needs two books that disagree by more than that margin. Add the implied chance of the best price on one side to the implied chance of the best price on the other. Under 100%, the pair pays more than it costs. At 100% or over, it does not.
The stakes follow from the same numbers. Each side gets the total stake multiplied by its implied chance and divided by the sum, and either winning bet then returns the total stake divided by the sum.
A real pair that falls short
The closest game of the 14 was Pittsburgh at Tampa Bay, a moneyline market where the two books below disagreed about the favorite’s price.
| Side | Sportsbook | Decimal price | American price | Implied chance |
|---|---|---|---|---|
| Pittsburgh Steelers | FanDuel | 1.72 | about -139 | 58.14% |
| Tampa Bay Buccaneers | LowVig | 2.35 | +135 | 42.55% |
| Both sides | 100.69% |
Split $1,000 by the formula and $577.40 goes on Pittsburgh and $422.60 on Tampa Bay. Either winner returns about $993.12, so the pair loses $6.88 whoever wins. It is a small, certain loss.
It would take one more step in price to turn it. With Pittsburgh at 1.72, Tampa Bay has to be better than 2.389, about +139. With Tampa Bay at 2.35, Pittsburgh has to be better than 1.741, about -135.
The same game with one price moved
Suppose a third book had posted Tampa Bay at +145, which is 2.45 in decimal. That price is made up; no book in our read had it. Pittsburgh stays at the real 1.72.
| Step | Pittsburgh at 1.72 | Tampa Bay at 2.45 |
|---|---|---|
| Implied chance | 58.14% | 40.82% |
| Stake from $1,000 | $587.53 | $412.47 |
| Return if it wins | $1,010.55 | $1,010.55 |
The two implied chances add up to 98.96%, so the pair returns $1,010.55 on $1,000 staked. That is $10.55, a little over 1%, and it needs both bets accepted in full at those prices.
Why arbitrage betting is hard in practice
Every figure above assumes two bets placed at the same moment, in full, and settled as written. Each assumption can fail, and a failure can leave you holding a plain bet on one side.
- The price moves: you bet Pittsburgh first and Tampa Bay drops from 2.45 back to 2.35 before the second bet is in. A Pittsburgh win still makes $10.55. A Tampa Bay win now returns $969.30, a loss of $30.70.
- The stake is cut: FanDuel’s Massachusetts house rules, effective July 30, 2026, reserve the right “not to accept certain Sportsbook bets, or to scale back the stakes (on a per user or aggregate basis).” If the second book takes only $200 of the $412.47, a Pittsburgh win makes $223.02 and a Tampa Bay win loses $297.53.
- A bet is voided: the same rules list among potential obvious errors odds that are “materially different from those available in the general betting market at the time the bet was made,” and say such a wager can be voided with the regulator’s approval. A price far enough out of line to open an arbitrage can fit that description. With the Tampa Bay bet voided, what is left is $587.53 on Pittsburgh: up $423.02 or down $587.53.
- The account is limited: the same rules let the book “set a lower or higher maximum bet wager amount per customer.” Our guide to why sportsbooks limit players covers what the house rules allow.
The size of the return matters too. The made-up pair ties up $1,000 across two accounts to make $10.55, and one moved price costs $30.70, nearly three times the gain.
How it differs from a hedge and from matched betting
A hedge uses the same stake arithmetic on a bet you already hold. You bet one side first, the price moves your way, and you bet the other side later to lock in part of the gain. Our hedging guide works through a $100 bet at +300 hedged with $240 at -150, which ends up $60 ahead either way. An arbitrage places both bets at once and needs no earlier position.
Matched betting also backs both sides, but its return comes from a sportsbook’s bonus bet and not from a pair of prices under 100%. The prices in a matched bet can add up to 104.76% like any other pair. Our guide to matched betting shows the two stages and what its terms can cost.
Prices: up to 11 sportsbooks a game via Nucleus, each book’s latest moneyline as seen on October 13, 2026, at 05:10 UTC. The feed carries decimal prices to two places, so the American prices are conversions.