Arbitrage Betting Explained

What is arbitrage betting?

Arbitrage betting (often shortened to “arbing”) means betting on every possible outcome of the same event, using different odds from different sources, so that — on paper, if every bet is accepted at those prices and settles under matching rules — your combined return is more than your total stake whatever happens. Fees, rejected or limited bets and rule differences can wipe that out. It works because odds sometimes disagree enough that the implied probabilities add up to less than 100%. Using FACTS: $100 split across odds of 2.10 and 2.05 returns $103.73 — a profit of $3.73, a 3.73% ROI. It’s a math exercise, not a prediction. We don’t take bets, promote bookmakers, or give tips — slipmath just explains and calculates the numbers.

How the math works

Every set of odds implies a probability. For decimal odds, implied probability is 1 ÷ odds. For American odds, the formula differs depending on sign: for positive odds like +110, it’s 100 ÷ (100 + 110); for negative odds like −110, use the absolute value: 110 ÷ (110 + 100). Add up the implied probabilities for all outcomes in a market and you get the “implied total.”

• If the implied total is under 100%, there’s an arbitrage opportunity — the odds overlap in your favor.
• If it’s over 100%, there’s no arbitrage and covering all outcomes proportionally guarantees a loss; at exactly 100%, it breaks even. In practice, the bookmaker’s margin (the “vig”) usually pushes markets above 100%. For a deeper look at this margin, see our guide on what vig is in betting.

To split your stake correctly across outcomes, you need to weight each bet according to its implied probability, not just split evenly. That’s where a dedicated tool like our arbitrage calculator helps — it does the proportional math for you.

Worked example: a two-way arbitrage

Take a two-outcome market (like a tennis match) priced at 2.10 on one side and 2.05 on the other. In American odds, that’s equivalent to +110 and +105.

Here’s what the numbers look like for a $100 total stake, from FACTS:

Metric	Value
Implied total	96.40%
Stake on 2.10 (+110)	$49.40
Stake on 2.05 (+105)	$50.60
Total return	$103.73
Profit	$3.73
ROI	3.73%

Because the implied total is 96.40% (under 100%), splitting $100 into $49.40 and $50.60 returns a calculated $103.73 whichever side wins — a $3.73 profit, or 3.73% ROI on the $100 risked — provided both bets are accepted in full at those prices and settle under the same rules. That ROI number matters more than the dollar profit: arbitrage margins are usually thin, so the money made scales with how much you’re able to stake, not how often you find opportunities.

A three-way market example

Arbitrage isn’t limited to two-outcome markets. A three-way market — like a soccer match with win/draw/win outcomes — priced at 2.20, 3.80, and 4.50 is worth checking the same way. Running the numbers from FACTS:

Metric	Value
Implied total	93.99%
Stake on 2.20	$96.72
Stake on 3.80	$56.00
Stake on 4.50	$47.29
Total return	$212.78
Profit	$12.78
ROI	6.39%

With an implied total of 93.99% — well under 100% — the prices form an arbitrage on paper. Spreading $200 across all three outcomes in these proportions returns a calculated $212.78 whichever result comes in, if all three bets stand as placed — a $12.78 profit (6.39% ROI). This is exactly why checking the implied total before staking anything is the single most important step: it tells you upfront whether a genuine opportunity exists before you commit any money.

What happens without arbitrage odds

For comparison, it’s worth seeing what a “normal” bet looks like when there’s no pricing mismatch. If you stake $100 split evenly across two outcomes both priced at 1.90, the implied total is 105.26% — well over 100%, meaning there’s a built-in margin working against you. In that scenario, FACTS shows a return of $95.00, a $5.00 loss, no matter which side wins. This is the default state of most betting markets: the implied total sits above 100%, and only specific, often short-lived, mismatches push it below.

Execution risk: why it’s not “risk-free”

Arbitrage math assumes both (or all) bets get placed at the exact odds you calculated with. In practice, several things can break that assumption:

• Odds can move. Between placing your first and second bet, the price can shift, turning a profitable split into a losing one.
• Palpable error voids. If a bookmaker later rules that a price was a clear mistake, that leg of your arbitrage can be voided, leaving you exposed on the other side.
• Different settlement rules. Markets can settle differently for things like overtime, extra time, or how pushes are handled — see our guide on what a push is in betting for an example of a result that doesn’t resolve as a straightforward win or loss.
• Limits and account restrictions. Accounts that place frequent arbitrage-style bets are sometimes limited or restricted, which can shrink or end future opportunities.

Because of these factors, arbitrage betting is never truly “risk-free” or “guaranteed,” even when the math on paper looks clean.

Common mistakes

• Splitting stakes evenly instead of proportionally. An even $50/$50 split doesn’t match the odds’ implied probabilities and can turn a profitable arb into a loss.
• Ignoring the implied total before staking. As the two-outcome 1.90/1.90 example shows, a total over 100% (105.26%) means there’s no edge, even if the odds look attractive.
• Placing bets too slowly. Odds move; a delay between your first and second bet can erase the small margin an arbitrage relies on.
• Overlooking different settlement rules. Two markets on the same event can resolve overtime or voids differently, breaking the arbitrage after the fact.
• Not accounting for fees or restrictions. Any added cost or limited stake size can turn a thin 3.73% ROI into nothing.

FAQ

What is arbitrage betting? Arbitrage betting means placing stakes on all possible outcomes of an event at odds whose implied probabilities add up to less than 100%, so that — if every bet is accepted at those prices and settles under matching rules — the calculated return is the same whichever result happens. For example, $100 split across odds of 2.10 and 2.05 returns $103.73, a profit of $3.73.

Is arbitrage betting guaranteed profit? It’s not truly guaranteed. Odds can move before both bets are placed, bets can be voided for palpable error, and settlement rules can differ between markets, all of which can turn a planned arbitrage into a loss.

What is the implied total in arbitrage betting? It’s the sum of the implied probabilities of every outcome’s odds. An implied total of 96.40% signals an arbitrage opportunity, while a total over 100%, like 105.26%, means there’s no arbitrage and a proportional all-outcome stake locks in a loss.

Can arbitrage betting go wrong? Yes. If odds move between placing your two bets, or if accounts get limited for consistent arbitrage activity, the opportunity can disappear or turn negative. A separate example — $100 split across two outcomes both priced at 1.90 — shows a $5.00 loss when the implied total is over 100% (105.26%).

If you choose to explore arbitrage betting, treat it as a math exercise with real execution risk, bet only what you can afford, and gamble responsibly (18+ in the UK, 21+ in most US states).