Arbitrage betting, often called arbing, is the practice of placing bets on all possible outcomes of an event at different bookmakers or exchanges to guarantee a profit regardless of the result. It exploits price differences between platforms. When one platform offers higher odds than another's lay price on the same outcome, a risk-free return can be locked in.
Exchanges play a central role in modern arbitrage because they allow you to lay outcomes, making it possible to arb between a sportsbook and an exchange, or even between two exchanges.
Arbitrage exists when the implied probability of all outcomes in a market sums to less than 100% across different platforms. This is the opposite of the bookmaker overround, which sums to more than 100%.
Arbitrage condition:
Sum of implied probabilities < 100%
When this condition is met, you can stake proportionally on each outcome and lock in a profit before the event even starts.
The simplest form of arbitrage involving an exchange is a back-to-lay arb:
Alternatively, you can arb between two exchanges — backing on one exchange where the price is high and laying on another where the price is lower.
Scenario:
Sportsbook A offers odds of 2.10 for Team A to win.
Exchange lay price for Team A is 2.00.
You back Team A at the sportsbook for £500 at 2.10.
You lay Team A at the exchange for a calculated stake at 2.00.
Lay stake calculation:
Lay stake = (Back odds × Back stake) ÷ Lay odds
Lay stake = (2.10 × £500) ÷ 2.00 = £525
Outcome if Team A wins:
Sportsbook profit: £500 × (2.10 − 1) = £550
Exchange loss: £525 × (2.00 − 1) = £525
Net profit: £550 − £525 = £25
Outcome if Team A loses or draws:
Sportsbook loss: −£500
Exchange win: £525 (minus commission)
Net profit: £525 − £500 = £25 (minus commission)
After accounting for exchange commission of 2% on the winning lay:
Exchange win: £525 × 0.98 = £514.50
Net profit if Team A loses: £514.50 − £500 = £14.50
Net profit if Team A wins: £25
The profit is slightly asymmetric due to commission, but it is guaranteed in both outcomes.
Two exchanges may have slightly different prices due to liquidity differences or temporary market inefficiencies.
Scenario:
Exchange 1 offers a back price of 2.04 on Team B.
Exchange 2 offers a lay price of 1.98 on Team B.
You back at Exchange 1 for £1,000 at 2.04.
You lay at Exchange 2 for £1,000 at 1.98.
If Team B wins:
Back profit: £1,040
Lay liability: £980
Net profit: £60 (minus commission)
If Team B loses:
Back loss: −£1,000
Lay win: £1,000 (minus commission)
Net result: approximately break-even or small loss after commission
This is not a true arb because the prices do not create a profit in both outcomes after commission. For a genuine arb, the lay price must be lower than the back price after adjusting for commission.
Correct exchange arb example:
Exchange 1 back price: 2.10
Exchange 2 lay price: 2.02
Lay stake = (2.10 × £500) ÷ 2.02 = £519.80
If selection wins: £550 − £530 = £20 profit
If selection loses: −£500 + £519.80 − £10.40 commission = £9.40 profit
Guaranteed profit exists in both outcomes.
The most common form. You find price differences before an event starts and place all bets simultaneously. The profit is locked in regardless of the result.
Prices move rapidly during live events. Arbs appear and disappear within seconds. This requires fast execution, often using software tools. The risk of one leg not matching is higher.
Backing on one exchange and laying on another. This can be profitable when one exchange has not yet adjusted to new information or when liquidity differs between platforms.
Backing at a sportsbook and laying at an exchange. Sportsbooks sometimes offer boosted prices or are slow to react to market moves, creating arb windows.
Placing an accumulator at a sportsbook and laying each leg sequentially at an exchange. More complex but can produce larger guaranteed returns when done correctly.
To determine if an arbitrage opportunity exists, convert each outcome's odds to implied probability and sum them.
Formula:
Implied probability = 1 ÷ Decimal odds
Example with two outcomes (tennis match):
Player A to win: odds 2.10 (implied 47.62%)
Player B to win: odds 1.95 (implied 51.28%)
Sum: 98.90%
Since the sum is less than 100%, an arbitrage opportunity exists. The theoretical profit is 1.10% of total stakes.
Three-outcome example (football match):
Home: 2.60 (38.46%)
Draw: 3.20 (31.25%)
Away: 3.40 (29.41%)
Sum: 99.12%
An arb exists with a theoretical profit of 0.88% if you can find these odds across different platforms.
To equalise profit across all outcomes, you must distribute your total stake proportionally to the implied probabilities.
Formula for each outcome:
Stake on outcome = (Total investment × Implied probability of outcome) ÷ Sum of implied probabilities
Example:
Total investment: £1,000
Outcome A implied probability: 47.62%
Outcome B implied probability: 51.28%
Sum: 98.90%
Stake on A: (£1,000 × 0.4762) ÷ 0.989 = £481.50
Stake on B: (£1,000 × 0.5128) ÷ 0.989 = £518.50
Profit regardless of outcome: approximately £11.00, or 1.1% of the total investment.
Arbitrage opportunities often last only seconds or minutes. Odds move quickly as other arbers and the market react. Manual arbing is nearly impossible on fast-moving markets. Software tools are almost essential.
The exchange lay side may not have enough money available at the required price. You may only get a partial match, leaving part of your back bet exposed.
Commission reduces the profit on the exchange leg. Many apparent arbs disappear once commission is factored in. Always calculate net of commission before placing any arb.
Sportsbooks actively identify and restrict or close accounts of consistent arbers. Using multiple sportsbooks, varying stakes, and not always taking the maximum available can prolong account life, but the risk remains.
Some sportsbooks and exchanges have different rules on voided bets, dead heats, or match abandonment. A bet that is voided on one platform may stand on another, creating unexpected exposure.
If arbitrage involves platforms in different currencies, conversion fees and exchange rate fluctuations can reduce or eliminate the margin.
Arbitrage requires constant monitoring of odds across multiple platforms. The margins are typically small, often 0.5–2%. Significant profits require either large stakes or very high volume, which increases both risk and account restriction probability.
Arbitrage and value betting are related but distinct:
| Aspect | Arbitrage | Value Betting |
|---|---|---|
| Risk | None (if executed perfectly) | Variance and losing streaks |
| Profit timing | Locked in before event | Realised over many bets |
| Frequency | Occasional, short-lived | More frequent opportunities |
| Account restriction risk | Very high | Moderate |
| Required bankroll | Large, spread across platforms | Moderate, can grow gradually |
| Long-term sustainability | Difficult due to restrictions | More sustainable with discipline |
Value betting accepts variance in exchange for more frequent and sustainable edges. Arbitrage offers guaranteed returns but is harder to maintain long-term due to account restrictions and the speed required.
Arbitrage using exchanges is a mathematically sound strategy that exploits price differences between platforms. The exchange's ability to lay outcomes makes it the perfect counterpart to sportsbook back bets or back bets on other exchanges.
The profit per arb is typically small — often less than 2% — so success depends on volume, speed, and precise execution. Exchange commission, liquidity, and the risk of sportsbook account restrictions are the main obstacles.
For those with the right tools, discipline, and bankroll, arbitrage remains a legitimate method of extracting risk-free profit from betting markets. But it is a short-term advantage for most. The markets correct quickly, the accounts get restricted, and the margins tighten. Sustainable betting success usually comes from value betting and trading — where exchanges once again provide the essential infrastructure.
