The following are the well-known factors for working out bookmakers percentages on a race.  Lets look at them – then explain them in better detail.

Decimal Price

Pre Decimal Price

Percentage Factor

$1.10

1/10

90.9

$1.11

1/9

90.0

$1.13

1/8

88.9

$1.14

1/7

87.5

$1.17

1/6

85.7

$1.20

1/5

83.3

$1.22

2/9

81.8

$1.25

1/4

80.0

$1.27

4/15

79.0

$1.29

2/7

77.8

$1.31

4/13

76.5

$1.33

1/3

75.0

$1.36

4/11

73.3

$1.40

2/5

71.4

$1.44

4/9

69.2

$1.50

1/2

66.7

$1.53

8/15

65.2

$1.57

4/7

63.6

$1.63

8/13

61.9

$1.67

4/6

60.0

$1.70

8/11

58.8

$1.80

4/5

55.6

$1.90

9/10

52.6

$2.00

1/1

50.0

$2.10

11/10

47.6

$2.11

10/9

47.4

$2.25

5/4

44.4

$2.38

11/8

42.1

$2.50

6/4

40.0

$2.63

13/8

38.1

$2.75

7/4

36.4

$2.88

15/8

34.8

$2.90

19/10

34.4

$3.00

2/1

33.3

$3.25

9/4

30.8

$3.50

5/2

28.6

$3.75

11/4

26.7

$4.00

3/1

25.0

$4.25

13/4

23.5

$4.50

7/2

22.2

$4.75

15/4

21.1

$5.00

4/1

20.0

$5.50

9/2

18.2

$6.00

5/1

16.7

$6.50

11/2

15.4

$7.00

6/1

14.3

$7.50

13/2

13.3

$8.00

7/1

12.5

$8.50

15/2

11.7

$9.00

8/1

11.1

$10.00

9/1

10.0

$11.00

10/1

9.1

$12.00

11/1

8.3

$13.00

12/1

7.7

$15.00

14/1

6.7

$16.00

15/1

6.3

$17.00

16/1

5.9

$18.00

17/1

5.6

$19.00

18/1

5.3

$20.00

19/1

5.0

$21.00

20/1

4.8

$26.00

25/1

3.9

$31.00

30/1

3.2

$34.00

33/1

2.9

$41.00

40/1

2.4

$51.00

50/1

2.0

$60.00

60/1

1.6

$67.00

66/1

1.5

$81.00

80/1

1.2

$101.00

100/1

1.0

13/1 odds intentionally left off for superstitious people!

You will note that the “Decimal Price” multiplied by the “Percentage Factor” equals 100 or fractionally close.

Let’s take an example of then how to work out where bookmaker’s percentages are on any race.

Let’s draw up a field of 8 runners with prices

 

Decimal Odds

Pre Decimal Odds

Percentages

Might and Power

$2.00

1/1

50.0

Saintly

$4.00

3/1

25.0

Octagonal

$5.50

9/2

18.2

Nothin Leica Dane

$8.00

7/1

12.5

Lonhro

$10.00

9/1

10.0

Intergaze

$13.00

12/1

7.7

Filante

$13.00

12/1

7.7

Radish

$101.00

100/1

1.0

 

 

Total %

132.1

So we see the bookmaker is betting to a percentage of 132.1% which is far too much in the bookmakers favour.  I want to have $100 on Might and Power - do I do it now or later?   Well, the answer is clearly do it later as Might and Power can actually ease out to 2/1 with a bookmaker percentage factor of 33.3 (at that price) and the bookmaker will then be betting to a percentage of a more realistic 115.4% (ie. original 132.1 minus 16.7).  The 16.7 figure is the difference between the even money factor at 50.0% and the 2/1 factor at 33.3%.   The bookmaker may not ease Might and Power to 2/1 but decide to ease 2 or 3 horses that are well in the market out slightly which will have the same effect on percentages.  The bookmaker will never have the percentage total reading under 100 for all runners or he/she is hoping to lose!   So if his/her percentage totals 90 – he/she is looking at losing 10% of their hold so that would be pretty silly business also.

In a perfect world the bookmaker used to be able to set his book and lay every runner in every race but those days are long gone.

TAB’s technically work to win and place, trifecta, quinella etc percentages of between 115% to 120% as Government taxes are payable by TAB’s on every dollar invested by a punter through a TAB outlet – and the tax amount comes out of each pool before the dividends are declared. Similarly bookmakers have fixed costs such as staff wages, turnover tax, fielding fees to clubs, etc. so they too must set their book in their favour to cover those fixed costs and run their business at a profit.  Most punters consider around 115% to be a fair percentage for bookmaker’s odds to total.   A fair rule is if their current displayed percentage is 130% or higher just stand back and wait – the horses well in the market have to ease out or it’s a one way street – and the bookie will win again.

I hope that gives you an overview in layman’s terms.  Once you have the factors you can sit down and work out the percentages for yourself.

Oh and as for that fictitious race – it was “red hot” as Radish won it – in the biggest boilover since Polly put the kettle on! Ajax got beaten at 40 – 1 ON in a 3 horse field – now Radish wins at 100 –1. It’s all too much. I’m off to take up knitting!