Arbitrage Betting Explained: How Arbing Works

Arbitrage betting, often called arbing, occurs when differences in odds between bookmakers create an opportunity to cover every possible outcome of a market while producing the same theoretical return.

Instead of trying to predict which team or player will win, an arbitrage bettor compares prices across different bookmakers and looks for combinations where the combined implied probability is below 100%.

When that happens, correctly calculated stakes can produce a theoretical profit regardless of which covered outcome wins. However, arbitrage isn't literally risk-free: odds can change, bets can be rejected or limited, markets can be settled differently and mistakes in execution can turn an apparent arb into a loss.

How Do You Find an Arbitrage Bet?

For a two-outcome market with decimal odds, convert each price into its implied probability:

Implied Probability = 1 ÷ Decimal Odds

Suppose Bookmaker A offers 2.45 on Outcome A while Bookmaker B offers 1.75 on Outcome B.

Outcome A: 1 ÷ 2.45 = 40.82%
Outcome B: 1 ÷ 1.75 = 57.14%

Add those probabilities together:

40.82% + 57.14% = 97.96%

Because the total is below 100%, these prices create a theoretical arbitrage opportunity, assuming the two bets genuinely cover all possible outcomes under equivalent settlement rules.

How to Calculate Arbitrage Stakes

Once you've identified an arb, the bankroll needs to be divided so that the return is approximately equal whichever outcome wins.

A convenient method is to calculate the target payout first:

Target Payout = Total Stake ÷ [(1 ÷ Odds A) + (1 ÷ Odds B)]

Then calculate each stake:

Stake A = Target Payout ÷ Odds A
Stake B = Target Payout ÷ Odds B

Using a total bankroll of £300 and odds of 2.45 and 1.75:

Target Payout = £300 ÷ 0.97959 ≈ £306.25

The approximate stakes are therefore:

Outcome A at 2.45: £306.25 ÷ 2.45 = £125.00
Outcome B at 1.75: £306.25 ÷ 1.75 = £175.00

The total stake is £300.

If Outcome A wins: £125 × 2.45 = £306.25
If Outcome B wins: £175 × 1.75 = £306.25

The theoretical profit is therefore approximately £6.25, equivalent to about 2.08% of the £300 staked.

How Do You Calculate Arbitrage Profit?

The percentage return available from an arbitrage can be calculated from the combined implied probability:

Arbitrage Return % = (1 ÷ Combined Implied Probability - 1) × 100

In this example:

(1 ÷ 0.97959 - 1) × 100 ≈ 2.08%

That percentage represents the theoretical return if both wagers are accepted at the quoted prices and settled according to compatible rules.

Why Do Arbitrage Opportunities Exist?

Different bookmakers don't always price markets identically. Their odds can vary because of different trading models, customer activity, risk exposure or the speed at which each operator reacts to new information.

One bookmaker may therefore offer the strongest price on one side of a market while another offers the strongest price on the opposite side. Occasionally, those prices overlap enough to create an arb.

These opportunities can disappear quickly as bookmakers update their odds, which is why an apparent arbitrage should be recalculated using the prices actually available immediately before placing the bets.

Is Arbitrage Betting Risk-Free?

No. An accurately executed arb can remove much of the outcome risk associated with predicting the winner, but it introduces several forms of execution and operational risk.

Potential problems include:

Odds movement: one price can change before the second wager is placed.
Stake limits: a bookmaker may accept less than the amount required to balance the arb.
Rejected bets: one side may fail while the other has already been accepted.
Different settlement rules: bookmakers may treat overtime, abandoned events, player withdrawals or dead heats differently.
Market mismatch: two similarly named markets may not cover exactly the same outcomes.
Human error: entering the wrong stake, selection or price can remove the expected profit.
Voided wagers: one bookmaker may void a bet under circumstances where another settles its side normally.
Currency and transaction costs: fees or exchange-rate movements can reduce an apparent margin.

For these reasons, it's more accurate to describe arbitrage as a strategy designed to reduce or eliminate market-outcome exposure when executed correctly, rather than as guaranteed or risk-free profit.

Why Bookmakers May Limit Arbitrage Bettors

Sportsbooks manage their own commercial risk and may restrict customers whose betting activity they consider unprofitable or inconsistent with the type of action they want to accept, subject to their terms and applicable regulation.

This can include reducing maximum stakes or otherwise limiting account activity. Policies differ between operators, so bettors should read the relevant sportsbook's current terms rather than assume that every bookmaker handles arbitrage in the same way.

Attempting to disguise betting behaviour or circumvent account restrictions can also conflict with operator terms. If an account is limited, the appropriate approach is to understand and comply with the operator's rules.

Arbitrage Betting vs Value Betting

Arbitrage betting and value betting both involve finding favourable prices, but they're fundamentally different strategies.

A value bettor believes the probability of an outcome is greater than the probability implied by the bookmaker's odds. The bet can therefore have positive expected value while still losing.

An arbitrage bettor instead combines prices across multiple outcomes so that the theoretical payout exceeds the combined stakes whichever covered outcome occurs.

Value betting: accepts outcome risk in exchange for positive expected value.
Arbitrage betting: attempts to cover every outcome and profit from differences between prices.

What to Check Before Placing an Arbitrage Bet

Before treating two prices as an arb, verify:

Both wagers refer to exactly the same event and market.
Together, the selections cover every possible outcome required by the calculation.
The quoted odds are still available.
Both bookmakers will accept the required stakes.
The settlement rules are compatible.
Your stake calculation accounts for rounding and any relevant fees.
The expected profit remains positive after all costs.

An arbitrage calculator or odds-comparison tool can speed up the mathematics, but the underlying market and settlement conditions still need to be checked manually.

Is Arbitrage Betting Profitable?

Arbitrage betting can produce positive theoretical returns when genuine pricing discrepancies exist and every part of the trade is executed successfully. However, margins are often relatively small and opportunities can disappear quickly.

Long-term results depend not only on identifying arbs but also on execution, available stakes, bookmaker restrictions, transaction costs and settlement outcomes.

Arbitrage should therefore be viewed as exploiting a temporary pricing discrepancy, not as a guaranteed income strategy.

A Bettor's Perspective on Sports Arbitrage

The following Reddit discussion provides one user's explanation of sports arbitrage. It represents an individual perspective and shouldn't be treated as independently verified evidence of profitability or investment performance.

Explaining the concept behind sports arbitrage and why it is an investment and not gambling
by u/the_arbitrage_guy in investing

Disclaimer: This article is provided for research and informational purposes only and is intended for adults aged 18+. Gambling involves financial risk and profits are never guaranteed. If you choose to gamble, set limits and never wager money you cannot afford to lose. Always check an operator's current terms, market rules and licensing status before placing a bet. For safer gambling information and support in Great Britain, visit GambleAware or GAMSTOP.

Arbitrage Betting Explained: Your Introduction to Risk-Free Sports Profit

Arbitrage Betting Explained: Your Introduction to Risk-Free Sports Profit