Arbitrage Betting Risks and Common Mistakes, with Numbers
Arbitrage betting is often called risk-free. It is not: experienced arbers know the risks, and beginners usually learn them the hard way. Some risks come before you place a bet, some during, some after the bets are settled. Most can be prevented with a fixed routine, and the rest can be kept small. This guide lists them with a worked example for each, on the same surebet throughout: over 2.5 goals at 2.10, under 2.5 at 2.05, 1,000 staked, 3.7% profit (the math is in what is arbitrage betting).
Key takeaways
- A 3.7% surebet at 2.10 and 2.05 turns into a 1.1% one if the second price drops to 1.95 and you re-split, or into a possible 1.3% loss if you stake as planned.
- A 5% exchange commission cuts the same surebet from 3.7% to 2.4%.
- User errors (wrong event, wrong market, wrong stake, a missed second bet) are fully avoidable; price moves, voids, mixed rules and limits can only be managed.
- Rounding 493.98 and 506.02 to 490 and 510 keeps the surebet, with a profit of 2.9% to 4.6% depending on the result.
- Place the leg most likely to fail first: the soft bookmaker, the lower limit or the price most likely to move.
Two kinds of risk
- User errors happen because you make a mistake while placing bets. All of them are avoidable.
- Risks built into arbitrage come from the process itself: prices move, bookmakers void bets, rules differ, limits appear. You can avoid most of them and limit the damage of the rest.
User errors
| Mistake | Example |
|---|---|
| Different events | two matches between the same teams: men and women, a reserve side, a baseball double-header, the second leg of a cup tie a week later |
| Wrong outcome | a surebet on over/under 2.5 goals, but both bets placed on over |
| Wrong market | one bet on over 2.5, the other on under 1.5 |
| Wrong stakes | the split says 1,077 and 923; you round the first to 1,000 and forget to recalculate the second |
| Only one leg | you forget to place or confirm the second bet at a bookmaker with a two-step slip |
| Not enough balance | the first bet is placed before you notice the second account is short |
| Currencies | stakes calculated as if both accounts were in the same currency |
| Fees and commission | the exchange's commission left out of the split |
Each of these leaves you with an ordinary bet or a guaranteed loss. A checklist before every surebet removes them: same sport, competition, teams, date and kick-off time on all legs; same market and line; stakes recalculated after any change; balance checked on every account.
Risks built into arbitrage
The price moves while you bet
You place 493.98 on over at 2.10. When you go to place the under, the price has dropped from 2.05 to 1.95.
| What you do | Stake on under | Returns if over wins | Returns if under wins | Result |
|---|---|---|---|---|
| Stake as planned at 1.95 | 506.02 | 1,037.35 | 986.74 | +3.7% or −1.3% |
| Re-split at 1.95 | 531.97 | 1,037.35 | 1,037.35 | +1.1% on any result |
| Skip the second bet | 0 | 1,037.35 | 0 | an ordinary bet |
Re-splitting keeps a smaller surebet as long as the sum of 1/odds stays below 1 (here 0.4762 + 0.5128 = 0.989). Once it is above 1, you choose between a small certain loss and an open bet. The surebet calculator lets you fix the stake you already placed and recalculates the rest.
A bet is voided
Bookmakers void bets on obvious pricing errors, and a surebet built on an outlier price is often one. If the bookmaker voids that leg, the other leg stays as an ordinary bet. How to tell an error from a real chance is in palpable errors.
Rules differ between bookmakers
Different settlement rules can make both bets lose:
- Overtime: one bookmaker settles ice hockey on regular time, another includes overtime and shootouts.
- Retirements: when a tennis player retires, one bookmaker voids the match, another settles it once a set is completed, a third once a ball is struck. Back the two players at bookmakers with different rules and a retirement can void one bet while the other loses.
- Starting pitchers: some bookmakers void baseball bets when a listed pitcher changes.
- Postponements: one bookmaker voids a postponed match at once, another waits days for it to be played.
Check the rules of the sports you arb most at the bookmakers you use most, and avoid pairs of bookmakers with different rules on the same market.
Only one leg gets placed
The site freezes after the first bet, the market closes because the match starts, or the bet goes to manual approval and comes back rejected. Avoid surebets in the last minutes before kick-off, and place first the leg most likely to fail.
Limits and partial acceptance
A bookmaker accepts only part of your stake, or an exchange matches only part of it for lack of liquidity. The unmatched part leaves the surebet unbalanced, and you must re-split the rest at once. Regular arbing makes this more common: see bookmaker limits.
Commission, fees and currencies
Costs belong in the split before you bet:
- Exchange commission applies to net winnings. Under 2.5 backed on an exchange at 2.05 with 5% commission works like odds of 1 + 1.05 × 0.95 = 1.9975. The sum becomes 0.4762 + 0.5006 = 0.9768, and the profit falls from 3.7% to 2.4%.
- Currency conversion: a 3% fee to move money between a euro and a dollar account wipes out a typical surebet. Keep all accounts in one currency where you can.
- Taxes on stakes work like a lower price on every bet; with 12% on each stake the sum of 1/odds must fall below 0.88.
Bonus conditions
A bonus counts only after you meet its rollover. A limit that arrives halfway through the rollover can trap the bonus, and part of your deposit with it. Promotions are covered in advanced arbitrage strategies.
Rounding stakes
Exact stakes such as 493.98 and 506.02 give an arber away, and many round them. Rounding changes the result slightly:
| Stakes | Returns if over wins | Returns if under wins | Profit |
|---|---|---|---|
| 493.98 / 506.02 | 1,037.35 | 1,037.35 | 3.7% on any result |
| 490 / 510 | 1,029.00 | 1,045.50 | 2.9% or 4.6% |
| 500 / 500 | 1,050.00 | 1,025.00 | 5.0% or 2.5% |
As long as every scenario stays above the total staked, rounding keeps the surebet. The calculator rounds for you and shows every scenario.
A routine that prevents most of it
- Set the same time zone and, where possible, the same currency at every bookmaker.
- Know the rules for tennis, ice hockey, baseball and postponements at the bookmakers you use most.
- Check that every leg is the same event: sport, competition, teams, date and time.
- Check that every leg is the same market and line, unless it is a deliberate cross-market combination.
- Recalculate stakes after any change and confirm the balance on every account.
- Place first the leg most likely to fail: usually the soft bookmaker, the one with the lower limit or the faster-moving price.
- Record every bet, as described in how to start arbitrage betting.
At first this takes minutes per surebet; with practice it takes seconds. Good arbitrage betting software does part of it for you: it matches events, flags rule differences and hides outlier prices.
Is arbitrage betting worth the risk?
The risks are real but mostly controllable, and the profit per bet is small: a median 0.61% in our data. It comes from the gaps between bookmakers that set their prices separately, as we explain in how bookmakers make money. Whether arbitrage beats simply finding better prices is the question in value betting vs arbitrage betting.
Summary
Arbitrage carries two kinds of risk: user errors, which a checklist removes, and risks built into the process, which you manage. Price moves, voids, mixed rules, partial acceptance and costs can each turn a surebet into an ordinary bet or a loss. Recalculate after every change, include every cost in the split and place the riskiest leg first.
FAQ
Is arbitrage betting risk-free?
No. A correctly calculated surebet guarantees a profit only if every bet is accepted at the planned price and settled the same way. Price moves, voided bets, different rules and partial acceptance can each turn it into an ordinary bet or a loss.
What is the biggest risk in arbitrage betting?
For most arbers it is the price moving between the first and the second bet. You can usually re-split and keep a smaller surebet, but sometimes you are left choosing between a small loss and an open bet.
Which bet of a surebet should I place first?
The one most likely to fail: usually the soft bookmaker's price, the bookmaker with the lower limit, or the price most likely to move. Once it is accepted, the other leg at a sharp bookmaker or exchange is easier to place.
Does exchange commission matter in a surebet?
Yes. Commission applies to net winnings and lowers the effective odds: 2.05 with 5% commission works like 1.9975, which cuts a 3.7% surebet to 2.4%.
Can I round surebet stakes?
Yes, as long as every scenario still returns more than the total staked. Rounding 493.98 and 506.02 to 490 and 510 keeps a profit of 2.9% to 4.6%, depending on the result.