Arbitrage betting explained: how sports arbs work
Books disagree. Occasionally they disagree so much that backing both sides at two different books returns more than you stake, whatever happens. That is an arbitrage. It is real, it is small, and it comes with more risk than the name “sure bet” suggests.
How an arb forms
On one book both sides of a market add up to more than 100% implied — that is the book’s margin. But you can take each side from a different book. If book 1 is slow to move one way and book 2 the other, the best price on each side can add up to less than 100%.
stake A = total × pA / (pA + pB) · return = total / (pA + pB)
Try your own numbers in the arbitrage calculator, or see the live list on the arbitrage edges page.
The risks
- Leg risk. Prices move between your first and second bet. Place the harder-to-get leg first, and know what you will do if the other side moves.
- Voids and palps. Books can cancel bets taken at an obvious error. If one leg is voided, you are left with a plain bet on the other side.
- Different rules. Make sure both bets settle the same way — overtime included or not, listed pitchers in baseball, what happens if a game is postponed.
- Limits. Books cap stakes, sometimes after you click, and may limit accounts that bet arbs regularly.
- Rounding and money movement. Round stakes to amounts that look normal, and remember deposits, withdrawals and any fees eat into a 1–2% margin.
How vigged finds arbs
For every game and market, the arbitrage tab takes the best live price on each side at the main line across the US books on the board, and lists the market when the two add up to under 100%. It skips stale and suspended quotes and reference-only sources you cannot bet in the US. The list updates as prices change — arbs often last only seconds to minutes, so confirm both prices at the books before betting.
Frequently asked questions
What is arbitrage betting?
Arbitrage (an arb or sure bet) is backing every outcome of an event at different books whose prices together imply less than 100%. With the right stakes, the return is the same whichever side wins, as long as both bets stand at the prices taken.
Is arbitrage betting legal?
Betting at more than one licensed sportsbook is legal where sports betting itself is legal. Books are allowed to limit or close accounts they see as arbitrage players, and their house rules on errors and voids apply. Sports betting is legal only in some US states.
How much can you make from an arb?
Most pre-game arbs between major US books return around 0.5–3% of the total staked. Bigger numbers usually mean a stale or wrong price that is likely to move or be voided.
Is arbitrage risk-free?
No. The main risks are a price changing before the second bet goes in, a bet being voided or canceled, the two books settling the market under different rules, stake limits, and account restrictions. Any of them can turn an arb into a loss.
How do I calculate arbitrage stakes?
Convert both prices to implied probability. Stake on each side = total stake × that side’s implied probability ÷ the sum of both. Return = total stake ÷ the sum. The arbitrage calculator does this for you.
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