What is The Bookmakers OverRound ?

You may have heard advanced punters talking about betting Overround when discussing bookmakers offered odds.

The Overround is simply a calculated figure that indicates the bookmakers theoretical profit percentage on any given market.

Probably the best way to explain is by simple example.

Lets look at how Bet365 price up the Man Utd V Arsenal match on 24/10/2004

Man Utd
Fractional Style
Decimal Style

Using Fractional style odds we would calculate the Overround as follows.

O = (1/ (1+home odds) ) + ( 1/ (1+draw odds) ) + (1/ (1+away odds) )

O = (1/ (1+13/8) ) + ( 1/ (1+2) ) + (1/ (1+7/4) )

Get your calculater out and that works out to be 1.08 when rounded up.


Using Decimal style odds the calcualtion is a little easier.

O = (1/ home odds) + ( 1/ draw odds) + ( 1 / away odds)

This of course gives the same answer of 1.08


What the 1.08 figure indicates is that the bookmaker has set his odds to make an 8% profit on all stakes taken on that match ..no matter who wins.

This assumption assumes that actual stakes of bets placed will fall in line with his expectations.


From a punters point of view an appreciation of over round is important.

It is a key indicator as to the profit potential of the market you intend to playing in.

The higher the over round figure, the higher the advantage to the bookmaker.


Also it is worth noting that although the example above is a typical soccer betting example, the same calcualtion principle can be applied to any betting event.

Say a horse race.

The easiest way is to work to decimal style odds, then sum up for all the runners.

eg O = (1/ odds1 ) + (1/ odds2 ) + (1/ odds3 ) + (1/ odds4 ) + etc etc.


Practice Exercise.

Take a football match similar to the above.

1. Calculate the overround using the odds from just a single bookmaker of your choice.

2. Repeat the exercise but this time instead of using the odds from a single bookmaker, select the best available odds for each outcome from a range of bookies.

Do you expect the Overround to be higher or lower?

What does that teach you?


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