Sports arbitraging (also called betting arbitrage, miraclebets, surebets) is a particular way of arbitrage. The main idea of sports arbitraging is betting markets due to either bookmakers’ opinions on event outcomes or plain errors. If the person doing sports arbitraging places one bet for each possible outcome at different betting companies, the bettor can make profit no matter what the outcome is. Usually bookmakers don’t have any issues with this, as long as the bettor uses different companies for each bet.

Slang refers to those who are doing sports arbitraging arbers; arbitrage is an arb. One arber can win typically around 2%, but profits around 4-5% can be also achieves. There are special events when an arber can make 20% profit. Arbitrage betting usually involves larger sums of money than at normal betting. There is also betting investment, which means placing relatively small bets on overvalued odds. Most of these will loose, but some will make profit.

The arbitrage described below takes advantage of different odds offered by different bookmakers. We consider an event with 2 possible outcomes. The idea is the same for events with more outcomes. The 2 bookmakers have different ideas about who has the best chances of winning. They offer the following fixed-odds gambling on the outcomes of the event:

	Bookmaker 1	Bookmaker2
Outcome 1	2.4	2.0
Outcome 2	1.55	1.8

The sum of the inverse of all outcomes of an event will always be greater than 1 for an individual bookmaker.

1 / 2.4 + 1 / 1.55 = 1.062 and 1 / 2.0 + 1 / 1.8 = 1.056

The bookmakers return rate is the fraction above 1, in other words: this is how much the bookmaker earns on offering bets at this event. Therefore Bookmaker 1 will earn 5.6% on bets on this event. Usually this gap will be between 8% and 12%.

The idea of arbing is to find odds at different bookmakers, where the sum of the inverse of all the outcomes are below 1. This means the bookmakers have a disagreement on the chances of outcomes. This can be used to make a profit.

If somebody places a bet on outcome 1 at bookmaker 2 and outcome 2 at bookmaker 1 this is what happens:

1 / 2.4 + 1 / 2.0 = 0.917

If there is a bet of $545 on Outcome 1 with Bookmaker 2 and a bet of $455 on outcome 2 at bookmaker 1 would ensure the bettor a profit.

If Outcome 1 comes out, the bettor will collect $545 * 2.0 = $1090 from bookmaker 2. If Outcome 2 comes out, the bettor will collect $455 * 2.4 = $1092 from bookmaker 1. Therefore with an investment of $1000, the arber will collect a at least profit of $90 no matter the outcome of the event.

If the bettor wants to place stake $500 at Outcome 1, then he has to place $500 * Odds 1 / Odds 2 at outcome 2. This way he can even out the odds and can receive the same return, no matter what the outcome is. In other words if there are two outcomes: a 2/1 and a 3/1, if the arber covers the 2/1 with $500 and the 3/1 with $333, he will win $1000 at a cost of $833, giving a 20% profit. However, profit of sports arbitrage will be usually around 4% or less.

Because the mathematical formula is sound, it is very important there is no human mistake. The special web-based tool at www.arbicharge.com can help bettors to make the necessary calculations.