The idea in one minute
Every bookmaker builds a margin into its odds. Turn each outcome's odds into the chance it implies, add the chances up, and one bookmaker's prices always come to more than 100%. That excess is the bookmaker's cut.
Bookmakers do not all agree, though. If Bet9ja prices Over 2.5 goals at 2.10 and SportyBet prices Under 2.5 at 2.05, the chances implied by those two best prices add up to 96.4%. Anything under 100% is a gap. Back both sides in the right proportion and you collect the same amount whichever way the match goes. The locked-in difference is your profit. People call it an arb or a surebet.
Change the odds below to see the gap open and close.
The maths is certain. The execution is not. An arb is only risk-free if both bets are accepted at the prices you calculated, both settle the way you expect, and you can withdraw the money. Most of this guide is about those three conditions.
Why arbs exist
Bookmakers are competitors, and they are not perfectly in sync. Gaps open for a few common reasons:
- Different models and customers. One bookmaker may shorten a popular team's price because its customers back that team, while another does not.
- Slow repricing after news. Team news or an injury reaches bookmakers at different speeds, and the gap closes within minutes once everyone catches up.
- Mistakes. A price far from every other bookmaker is more likely an error than a gift. Bookmakers can void bets placed at obviously wrong odds.
- Promotions and boosts. Boosted odds can open arbs, but these are the ones bookmakers watch most closely.
- Live betting. In-play odds move fast and gaps are more common, but so are failed bets. More on that in the scenarios.
Guides report margins from about 0.5% to 5% per arb, with most football arbs around 1% to 3%. Windows last from a few seconds to a few minutes. A very large margin should make you suspicious, not excited.
The maths
Four lines are enough for every arb:
Arb exists when the implied chances of all outcomes add up to less than 1 (100%)
Stake on an outcome = bankroll × (1 ÷ its odds) ÷ total implied chance
Return = bankroll ÷ total implied chance, the same whichever outcome wins
Profit = return − bankroll, and margin = 1 ÷ total − 1
Two-way example (Over / Under 2.5)
| Outcome | Bookmaker | Odds | Implied chance | Stake |
|---|---|---|---|---|
| Over 2.5 | Bet9ja | 2.10 | 47.62% | ₦4,940 |
| Under 2.5 | SportyBet | 2.05 | 48.78% | ₦5,060 |
| Total | 96.40% | ₦10,000 |
Three-way example (1X2)
| Outcome | Bookmaker | Odds | Implied chance | Stake |
|---|---|---|---|---|
| Home win | Betpawa | 2.60 | 38.46% | ₦3,935 |
| Draw | Nairabet | 3.70 | 27.03% | ₦2,765 |
| Away win | Livescorebet | 3.10 | 32.26% | ₦3,300 |
| Total | 97.75% | ₦10,000 |
Three-way arbs need three bets placed close together at three bookmakers, so they are harder to execute than two-way arbs and usually pay 1% to 3%.
Rounding. Bookmakers take whole naira, so every stake moves by up to about ₦1 when you round it. On a thin margin that matters. After rounding, work out each payout again (stake × odds) and make sure they are still within a few naira of each other.
Placing an arb, step by step
Confirm the arb is still live
Open both bookmakers and check the odds yourself. The ARB RADAR feed refreshes about every 30 seconds, and prices can move faster than that.
Read the market rules
Check that the market, the line and the definition are identical. Does it include extra time? What happens if the match is postponed, abandoned or a player does not start? Different rules behind the same-looking market create fake arbs.
Check limits and balances
Make sure each bookmaker will accept the stake you need and that both balances cover it. Waiting on a deposit is how arbs get missed.
Place the lower-odds leg first
This is the ARB RADAR rule of thumb: place the lower-odds leg first, then the other. Many guides add that you should start with whichever price looks most likely to move or be limited. Pick the leg you would least want to miss.
Check the first slip, then recalculate
Confirm the first bet was accepted at the odds you expected. If the price changed, recalculate the second stake before you do anything else.
Place the second leg straight away
Do not leave the first bet hanging, and do not chase a worse price. If the arb has gone, see the scenarios below.
Confirm both bets and compare payouts
Open your bet history on both bookmakers. Both payouts should match within a couple of naira. A bigger gap means a wrong stake, a wrong selection or changed odds.
Record everything
Screenshot the slips and log the stakes, odds, bookmaker, time and result. You will need the log for tax and to see which bookmakers start limiting you.
When things go wrong
These are the scenarios that cost arbers money, from the most common to the slow-burning ones. Open each one to see what happens and what to do.
The odds move before your second betMost common
What happens
You now hold a normal, unhedged bet. If that result does not come in, you lose the stake. Guides call this the main immediate risk of arbing.
What to do
Recalculate at the new price. If the total is still under 100%, place the second bet. If not, look for the best alternative at a third bookmaker, cash out the first bet if your bookmaker offers it, and take the small loss. Never double the stake to win it back.
The second bookmaker rejects the bet or caps your stakeCommon
What happens
Only part of the arb is covered. The uncovered part is an ordinary bet.
What to do
Place the most you are allowed, then cover the rest at another bookmaker. Check each bookmaker's maximum stake before the first bet. If an account's limit keeps blocking you, stop using it for arbs.
A bookmaker voids a bet over an obvious errorSerious
What happens
Bookmakers can cancel bets placed at clearly wrong odds and return the stake. The other leg then stands alone with full risk.
What to do
Be suspicious of any price far from every other bookmaker. Read the bookmaker's rules on errors. If a leg is voided, treat the remaining bet as open exposure and consider hedging it.
The match is postponed, abandoned or suspendedSerious
What happens
Bookmakers differ on how long they wait and on when a bet voids or settles. One leg can void while the other stays open.
What to do
Read the abandoned-match and postponement rules at both bookmakers before staking. Be careful with matches that carry weather or fixture risk.
Extra time, penalties and what "full time" meansSerious
What happens
Most football markets settle on 90 minutes plus stoppage time, but some, such as "to qualify" or a match winner that includes overtime, count extra time and penalties. If one bookmaker counts extra time and the other does not, it is not an arb.
What to do
Compare the market name and rule text on both bookmakers. Match like with like. Treat cup knockouts with extra care.
A player does not start, or a tennis match ends in retirementSport-specific
What happens
Player markets usually void if the player does not play. In tennis, a retirement may void or settle bets depending on the bookmaker and how far the match had gone. Experienced arbers report losing money on rule differences like this across several sports.
What to do
Check the rule for that sport and market on both bookmakers. Skip player markets where there is an injury doubt.
Handicap and quarter linesAdvanced
What happens
Lines such as -0.25 or +0.75 split your stake, so part of a bet can win, lose or return. An arb across such lines is not a simple two-way and can lose in some outcomes if it is calculated like one.
What to do
Only trade them if your calculator is built for split stakes. If you are not sure, skip it.
Live (in-play) arbsHigher risk
What happens
Odds change in seconds, bets pass through an acceptance delay, and markets suspend after goals. The first leg can be accepted and the second rejected.
What to do
Stay pre-match until you are confident. If you go live, use small stakes, keep both bookmakers open and ready, and place the riskier leg first.
Your connection drops or the app freezes mid-betCommon
What happens
You cannot tell whether the bet went through. Pressing submit again can stake twice.
What to do
Open your bet history in that bookmaker before doing anything. Only re-submit once you know the first attempt failed. Keep mobile data as a backup to Wi-Fi.
You back the same side twice, or type the wrong stakeCostly
What happens
One experienced arber wiped out an entire snooker arb by betting the same player at both bookmakers. Beginners are more likely to make this slip.
What to do
Slow down. Read the selection name, the odds and the stake on every confirmation screen. Check that your two bets are on opposite outcomes.
A bookmaker limits or closes your accountSlow burn
What happens
Accounts that keep winning can get maximum stakes cut to very small amounts or be closed, often without a reason. Reports range from weeks to a few months. Some bookmakers' terms forbid arbitrage outright.
What to do
Expect it. Spread activity across several bookmakers, keep stakes sensible, and read each bookmaker's terms. Do not open duplicate accounts or use someone else's account.
Winnings are delayed, held or questionedPossible
What happens
Bookmakers can ask for identity checks before a withdrawal and can hold or void winnings if they believe their terms were broken. Withdrawals also have limits and processing times.
What to do
Finish identity verification before you need to withdraw. Learn each bookmaker's withdrawal limits and timings. Do not keep your whole bankroll at one bookmaker.
Your money is in the wrong placeEveryday
What happens
After an arb, the profit sits at the bookmaker where you won, and the other balance is lower. Slow deposits and withdrawals make you miss the next arb, since opportunities can vanish within seconds.
What to do
Keep a working balance at each bookmaker. Rebalance in batches rather than after every bet, because very frequent withdrawals can draw attention.
Bonuses and boosted oddsRead the terms
What happens
Promotional odds often come with rules: bonus funds, wagering requirements and excluded markets. Arbs built on promotions are the most closely watched.
What to do
Read the promotion terms first. Do not arb with bonus funds unless the terms clearly allow it.
Tax takes a slice of the winning legMargin killer
What happens
You win only one side of an arb, and tax on that side's winnings can swallow much of a thin margin. Chapter 08 works through an example.
What to do
Work out your profit after tax and fees before you place the bets, not afterwards.
The data on screen is a few seconds oldAlways
What happens
ARB RADAR reads odds from bookmakers and refreshes the feed about every 30 seconds. By the time you open the bookmaker, the price may have moved.
What to do
Treat the feed as a pointer, not a promise. Confirm the odds on the bookmaker's own page and recalculate if they differ.
Do and don't
DO
- Start small and with two-way markets, which are easier to execute.
- Check the odds yourself on both bookmakers before you stake.
- Read the rules on market definition, postponement and abandonment at both bookmakers.
- Check limits and balances before the first bet.
- Place the lower-odds leg first, then the other straight away.
- Confirm both bets were accepted and that the payouts match.
- Keep working balances at every bookmaker you use.
- Track every bet for tax and to spot which accounts are being limited.
- Work out profit after tax and fees before you stake.
- Treat accounts as finite and spread activity across bookmakers.
- Set a budget, take breaks, and stop if it is stressing you.
DON'T
- Don't read "guaranteed" as covering execution, voids, tax or account risk.
- Don't chase a worse price when the odds move. Hedge or take the small loss.
- Don't double a stake to win a loss back.
- Don't trust an outlier price far from the rest of the market.
- Don't mix markets with different definitions, such as 90 minutes against extra time.
- Don't use bonus funds for arbs without reading the terms.
- Don't open duplicate accounts, use someone else's, or share yours.
- Don't keep all your money at one bookmaker.
- Don't skip the confirmation screen. Wrong selections and stakes erase profits.
- Don't rely on arbing as income. Margins are thin and accounts do not last.
- Don't bet money you cannot afford to lose.
Money, accounts and limits
What to expect
Arbitrage is high volume and low margin. At a 2% margin, ₦10,000 staked earns about ₦200 and ₦100,000 earns about ₦2,000, before tax and before any mistakes. Guides suggest you need real capital spread across several bookmakers and a lot of time watching for gaps. One experienced arber describes returns of around 1% as typical and accounts being restricted as almost inevitable.
Managing accounts
- Round your stakes sensibly. A stake like ₦4,900 looks like a normal bet. ₦4,939.61 does not, and bookmakers only accept whole naira anyway. Recheck both payouts after rounding.
- Spread across bookmakers and markets. Heavy repeat use of one bookmaker or one obscure market draws attention.
- Don't only take outliers. Accounts that only ever bet prices far from the market stand out.
- Pace yourself. One experienced arber says moving too fast was what got his accounts restricted.
- Mixing in ordinary bets or varying stake sizes may delay limits. Guides agree it rarely prevents them.
- Keep records per bookmaker. Balanced results across bookmakers are easier to manage than one account that wins all the time.
Check each bookmaker's terms. Some forbid arbitrage and may limit, close or void as a result. ARB RADAR shows you prices. You are the one who places the bets and accepts the bookmakers' rules.
Tax and the rules in Nigeria
- Age. Betting is for adults aged 18 and over.
- Regulation. Gambling in Nigeria is regulated mainly at state level, for example by the Lagos State Lotteries and Gaming Authority, with a federal body, the National Lottery Regulatory Commission, also in the picture. Industry sources say the split between state and federal powers is still being worked out after a 2024 Supreme Court ruling. Check that your bookmaker holds a licence that covers where you live.
- Identity checks. Licensed bookmakers run know-your-customer checks under anti-money-laundering law. Use your own verified account only.
- Withholding tax on winnings. Reports say a withholding tax on gambling winnings has applied since January 2025, at 5% for residents and 15% for non-residents, deducted by licensed operators. How it is applied to each payout, and whether every state follows it, is still being clarified.
Why tax matters so much for arbs
An arb always has one winning bet and one losing bet. The tax, if it applies, falls on the winning side, and the losing stake is not refunded. Using the earlier example, the profit is ₦373. If 5% were taken from the winnings on the winning leg, that is about ₦270 and leaves roughly ₦100. If 5% were taken from the whole payout of ₦10,373, it is about ₦520 and the arb loses roughly ₦146.
That is an illustration, not tax advice. Ask your bookmaker exactly how withholding is applied to your payouts, and ask a qualified tax adviser what you owe. Then include it in your calculation before you stake.
Before-you-bet checklist
Tick each one honestly. Skip any, and you are no longer doing arbitrage, you are gambling on the gap.
Bet responsibly. Arbitrage reduces the risk of a result going the wrong way. It does not reduce the risk of mistakes. Only stake money you can afford to lose, and if betting is causing you stress or you cannot stop, step away and talk to someone you trust or a professional counsellor.
Sources and further reading
This guide is a plain-language summary of public sources, adapted for ARB RADAR users. The examples use made-up odds. Check current rules and tax treatment yourself.
- Top End Sports: Arbitrage betting
- SoccerNews: Betting arbitrage explained, how surebets work and what to expect
- Soccerway: Sure bet arbitrage explained
- LegalClarity: Arbitrage betting, how it works and what can go wrong
- RotoGrinders: Arbitrage betting guide
- The Rundown: Arbitrage Part III, drawbacks and opportunities
- SproBets: How to place and manage your arbitrage bets effectively
- Altenar: Nigeria sports betting and gambling laws (industry blog, not legal advice)
- IT Edge News: How Nigeria's new tax rules could reshape sports betting