How to Calculate the "Generosity" of Betting Sites

Blackboard bets: As we all know the odds vary between bookmakers and bookmaker, but how can you understand which bookmaker is the most generous, or offers the most value. The Blackboard Bet indicates the bookmakers potential for profit, the lower this figure is, the lower the bookmakers expected margin. But how is it calculated?

Bookmaker's margin =100/odd1+....+100/oddN

Here we have two, real life examples:

Match: Roma-Milan

on Pinnacle Sports: Roma to win =2.36 draw=3.34 Milan to win =3.39 As a percentage: %=100/2.36+100/3.34+100/3.39= 101.81

on Roma=2.40 draw=3.25 Milan=2.90 As a percentage: %=100/2.40+100/3.25+100/2.90=106.91

From here you notice that Pinnacle is very generous to the punter. Typically Italian bookmakers are not very "generous" with percentage around 108-114 even for the italian high tax. In contrast UK betting sites traditionally offer far more competive percentages of arround 101-105, this is because the UK market is one of the most competitive gambling markets in the world and cannot afford to offer such high odds, otherwise their punters would leave! What is certain is that you will never find the percentages offered by anybookmaker to be below 100 because otherwise this would lead to a case of a surebet and more than likely mean the bookmaker would not remain in business much longer.