Arbitrage calculator

How arbitrage betting works

Bookmakers don't always agree on the odds. When you take the best odds for each outcome of an event, often from different bookmakers, their combined implied probability can drop below 100%. That gap is an arbitrage, also called a surebet: you back every outcome and make a profit whatever the result.

To check, divide 1 by the decimal odds of each outcome and add up the results. If the total is below 1, there is an arbitrage. Arbilocus then splits your total stake in proportion to those shares, so every outcome pays out the same amount.

Example

In a tennis match, one bookmaker offers 2.10 on Player 1 and another offers 2.05 on Player 2. 1/2.10 + 1/2.05 = 0.964, so the odds add up to 96.4%. With a total stake of 100, you bet 49.40 on Player 1 and 50.60 on Player 2. Whoever wins, you get back about 103.73, a guaranteed profit of 3.73.

What else it can do

• Any odds format. Enter decimal (2.50), fractional (6/4), American (+150) or Asian odds (Hong Kong, Malay, Indonesian). Switch at any time and the odds you entered are converted.
• Betting exchange commission. Exchanges such as Betfair, Smarkets and Matchbook take a commission on winnings, often 2–5%. Enter it for each outcome and the stakes are worked out from the odds after commission.
• Fixed stake. If a bookmaker limits your bet, or you want an exact amount on one outcome, lock that stake and the other stakes follow it.
• All the profit on one outcome. Put the whole profit on the result you think is more likely. The other outcomes only pay back your total stake.
• Rounded stakes. Round to 1, 5 or 10 so your bets look like everyone else's.
• Two, three or more outcomes. Tennis and basketball winners, football 1X2, over/under and any other market.
• Copy and share. Copy the stakes as text, or send a link that opens the same calculation.

Questions

Is arbitrage betting legal?

In most countries it is not against the law. Many bookmakers' terms, however, let them limit your stakes or close accounts that regularly bet on arbitrage. Check the rules where you live and the terms of each bookmaker.

What can go wrong?

Arbitrage is low-risk, not risk-free. The usual problems, and what to do:

• The odds change while you bet. Odds can move in seconds. Place the bet whose odds are most likely to move first, then check the other price before you place it. If it has changed, enter the new odds and the stakes are worked out again.
• A bet is cancelled. If a bookmaker made an obvious mistake in its odds, its terms usually let it void the bet, and your other bet is left alone. Be careful with odds far above what every other bookmaker offers.
• Your stake is limited or refused. A bookmaker may accept less than you asked for. Fix the stake on that outcome with the lock button, enter the amount that was accepted, and Arbilocus works out the other stakes.
• Different rules for the same event. Bookmakers can settle bets differently, for example when a tennis player retires or a match goes to extra time. Check that every bet you place settles the same way.

Why round the stakes?

Amounts like 49.37 can make a bookmaker suspect arbitrage. Rounding to 1, 5 or 10 looks more natural. Rounding changes the payouts slightly, so Arbilocus always shows the lowest profit across all outcomes.

Does Arbilocus find arbitrage for me?

Not yet. You enter the odds you found, and Arbilocus works out the stakes and the profit.

Is it free? Do I need an account?

It is free and needs no account. The calculator runs in your browser, so the numbers you enter never leave your device. Your last numbers are kept in this browser, so they are still there when you come back. "Start over" clears them.