A bet on all possible outcomes of an event that guarantees a profit regardless of the result. It requires no probability estimation and no edge over the bookmaker — the profit is mathematically locked in. Most commonly, arbs involve two bookmakers, but they can span three or more, or exist across different markets within the same bookmaker.
Bookmaker A prices Team A at 2.10.
Bookmaker B prices Team B at 2.10.
You bet both sides and lock in profit.
How to Find an Arb
The formula for detecting arbitrage:
(1 / odds_A) + (1 / odds_B) < 1
If the sum of implied probabilities is below 100%, an arb exists.
Example
Bookmaker 1: Team A at 2.10, implying 47.6% probability Bookmaker 2: Team B at 2.10, implying 47.6% probability
1/2.10 + 1/2.10 = 0.952 = 95.2%
Sum is 95.2%, which is below 100%. That’s a 4.8% guaranteed return on your total stake.
To profit equally regardless of outcome, stake proportionally:
Stake A = Total × (1/2.10) / (1/2.10 + 1/2.10)
Stake B = Total × (1/2.10) / (1/2.10 + 1/2.10)
With $1,000 total: $500 on each side.
- If Team A wins at 2.10: $1,050 return
- If Team B wins at 2.10: $1,050 return
Profit: $50 either way.
Types of Arbitrage
Prematch arbs appear before an event starts. Returns are lower but you have time to place both sides.
Live arbs appear during the event when odds lag behind the actual game state. Returns are higher but you have seconds to act.
Cross-market arbs combine different markets on the same event within one bookmaker or across books. Back over 2.5 goals with one book and under 2.5 goals with another — if the combined implied probability is below 100%, it’s an arb.
Middles involve betting both sides of a spread or total to win both bets if the result lands in the middle range.
How to Calculate for 3+ Outcomes
For events with three or more possible outcomes (1X2, correct score), extend the formula:
(1 / odds_1) + (1 / odds_X) + (1 / odds_2) < 1
If the sum of all implied probabilities is below 100%, an arb exists. Stake proportionally across all outcomes using the same method as the two-outcome example.
Sports Where Arbs Are Most Common
Table tennis, esports, lower-tier football leagues, and women’s tennis produce frequent arbs. These markets attract less sharp money, so odds discrepancies between bookmakers last longer.
Premier League, Champions League, NFL, and NBA are rarely arbed — sharp syndicates scan them and odds converge within seconds.
Why Arbs Are Rare
Arbs exist because bookmakers disagree on pricing. They’re most common:
- Before market opens — early odds are less refined
- During fast-moving events — live betting odds lag behind
- Across markets — same event priced differently on different exchanges
- In niche sports — less sharp money means less efficient pricing
Mainstream markets with heavy volume are almost never arbed. The sharp bettors move the lines too fast.
Why Bookmakers Hate You
Arbitrage bettors are the most dangerous customers for bookmakers. Not because the loss from one arb is large, but because the pattern is detectable.
Bookmakers track:
- Betting patterns — consistently only betting when odds are favorable
- Cross-book activity — accounts linked to arbitrage networks
- Stake amounts — precise, proportional stakes (unlike recreational bettors)
- Timing — betting immediately when odds move
Once flagged, you get limited. Maximum stake drops significantly. Account restricted. Eventually banned.
This is legal. Bookmakers’ terms of service allow them to limit any account for any reason.
The Real Costs
Account Limitations
Each bookmaker account has a limited lifespan. Once limited, you need a new one. This means:
- New accounts in different names, using family members where possible
- Using betting exchanges instead of traditional books
- Constantly rotating between platforms
Time Investment
Finding arbs requires scanning odds across multiple books continuously. Manual scanning is tedious.
Execution Risk
Odds change fast. By the time you place both sides, one book may have already moved. You end up with a one-sided bet — no arb, just a regular wager.
Tax Implications
In some jurisdictions, gambling winnings are taxable. Arbitrage profit may be classified differently than recreational gambling.
Arbitrage vs Matched Betting
Matched betting uses bookmaker welcome offers and free bets to guarantee profit. Unlike arbitrage, it requires no odds discrepancies — you back and lay the same outcome to qualify for a bonus, then convert the free bet into cash.
Matched betting is more sustainable. Bookmakers expect bonus hunters and rarely limit them. But each offer is a one-time opportunity. Arbitrage can be repeated indefinitely but carries account limitation risk.
Using Betting Exchanges
Exchanges let you back or lay outcomes against other users. Exchange odds are often better than bookmaker odds. Exchanges charge commission instead of building margin into every price.
Common arb setups with exchanges:
- Back on an exchange, lay with a bookmaker
- Back with a bookmaker, lay on an exchange
- Back on one exchange, lay on another
Betfair and Matchbook are the largest exchanges. Access and commission rates vary by jurisdiction.
Cross-Exchange Arbitrage
When two exchanges disagree on odds for the same event, back on one and lay on the other. No bookmaker involvement means no account limitation risk.
Cross-exchange arbs are less common than bookmaker arbs but more sustainable.
Arbitrage vs Value Betting
| Arbitrage | Value Betting | |
|---|---|---|
| Profit | Guaranteed | Probabilistic |
| Risk | Zero with perfect execution | Positive |
| Returns | Low | Higher long-term |
| Account lifespan | Short | Longer |
| Scalability | Poor | Better |
| Requires edge | No | Yes |
Risk-free but low-return and unsustainable. Value betting is risky but scalable and more profitable over time.
Arbitrage is supplementary — grab it when you see it, don’t build a strategy around it.
Tools and Scanners
Software scanners track odds across dozens of bookmakers and alert you to arbs in real time.
- RebelBetting — polished interface, wide coverage, paid subscription
- BetBurger — strong live section, popular in CIS
- OddsJam — US-focused, different pricing model
- AllBestBets — CIS-focused, has a free tier
Most offer free trials. Factor the subscription cost into your expected returns.
Bankroll Management for Arbitrage
Distribute your bankroll across the bookmakers you use. Keep enough balance on each to place both sides without delay. A common rule: no more than 20% of total bankroll on a single bookmaker.
Common Beginner Mistakes
- Placing one side before confirming the other is still available — odds move and you end up with an unmatched bet
- Betting more than the max stake on the first side, then finding the second side has a lower limit
- Using round or precise stakes that trigger bookmaker alerts
- Ignoring withdrawal fees and processing time when calculating net returns
What You Actually Need
To make arbitrage work:
- Accounts at several bookmakers, or a combination of books and exchanges
- A way to move money between them quickly
- Software or alerts for odds movements
- Awareness that some bookmakers eventually limit or ban arb bettors