How to convert odds values to probability values

**Dunder** · 01-08-10, 02:31 PM

I have attached for you an excel spread sheet that will calculate what you asked for.
Unfortunately it is not that simple because the odds are not a true reflection of the probability.

For soccer betting the odds offered by a book (this tends to be the opposite of what happens for US Sports) are generally weighted such that the odds for the favourite have less juice than those for the draw and for the dog. A typical example would be

Team A 1.44
Draw 3.60
Team B 10.00

where the over-round/juice is 7.2%.

Unless we are talking about exchange odds however, we cannot simply add 7.2%.

A true reflection would be something like:

Team A 1.46
Draw 4.00
Team B 15.40

**Ramaliu** · 04-18-11, 06:39 AM

Hello,

Where is the spreadsheet???? How can I access it?

**the_mathman** · 04-18-11, 07:17 AM

Originally posted by Dunder

I have attached for you an excel spread sheet that will calculate what you asked for.
Unfortunately it is not that simple because the odds are not a true reflection of the probability.

For soccer betting the odds offered by a book (this tends to be the opposite of what happens for US Sports) are generally weighted such that the odds for the favourite have less juice than those for the draw and for the dog. A typical example would be

Team A 1.44
Draw 3.60
Team B 10.00

where the over-round/juice is 7.2%.

Unless we are talking about exchange odds however, we cannot simply add 7.2%.

A true reflection would be something like:

Team A 1.46
Draw 4.00
Team B 15.40

Good work Dunder.
In fact in the soccer betting the book preferr limit the edge on the favorite to offer best odds on it, so alle the edge is taken from the underdog quote.

Only a thing: Dunder you have forgot the excel file!!!

**Blax0r** · 04-19-11, 05:22 PM

Originally posted by armando

Is there a formula to convert an odds value to a probability value for example:

home tie visitor
If in a soccer match we have odds of 2.1 3.2 2.9

What is the probability for the home team win based in 2.1 odds, for the visitor win based in 2.9 odds and the tie based in 3.2 odds

I'll do the process for this example; then you guys can probably make your own spreadsheet.

H - 2.1
D - 3.2
A - 2.9

First let's figure out the implied probability of each of these positions with the EV equation:

(amount won)*p - (amount lost)*q = 0
(amount won)*p - (1 - p)*(amount lost) = 0
(amount won + amount lost)*p - (amount lost) = 0
p = (amount lost)/(amount won + amount lost)

where p is P(win) and q is P(loss).

H - 2.1 --> 1/2.1 = 47.62%
D - 3.2 --> 1/3.2 = 31.25%
A - 2.9 --> 1/2.9 = 34.48%

These are the necessary probabilities in order for you to have 0 EV (if you bet on one of these positions). However, this doesn't exactly indicate the true probability of the event since the book should be offering lower odds than the actual probability (ie, give themselves +EV).

This is now just reduced to a regular ratio problem that you guys probably saw on the SATs or middle school math.

H - 47.62
D - 31.25
A - 34.48
total: 113.35

The total should actually be 100, since P(A) + P(H) + P(D) = 1. I'll assume the book's juicing each position evenly, but you can easily modify this.

47.62 : 113.35 should be the same ratio as X : 100:
47.62/113.35 = X/100; solve for X.

H - 42%
D - 27.57%
A - 34.42%

These are the event's true probabilities implied by the book's odds; making an excel sheet to automate this is probably fairly simple.

**Jerome Morrow** · 04-20-11, 02:33 AM

^^
Can you describe more about the formula for excell?

**subs** · 04-22-11, 11:22 AM

look for ganchrow's post simple VBA functions or something. it is all there and much more.

if u gonna do it urself just go slowly 1 step at a time - it really easy this way. or just click the paperclip to get the posted excel.

good luck

**Salamander** · 04-22-11, 11:52 AM

Took me many months of adjusting to be able to do anything with Euro numbers.

1.25=80%
1.33 = 75%
1.43 = 70%
1.5 = 66.66%
1.66 = 60%
1.8 = 55.5%
2 = 50%
2.25 = 44.44%
2.5 = 40%
2.7 = 37%
2.85=35%
3= 33.3%
3.5=28.5%
4= 25%

Those are some key numbers I memorized, but it's still like learning to speak a foreign language.

**Blax0r** · 04-22-11, 12:37 PM

Originally posted by Salamander

Took me many months of adjusting to be able to do anything with Euro numbers.

1.25=80%
1.33 = 75%
1.43 = 70%
1.5 = 66.66%
1.66 = 60%
1.8 = 55.5%
2 = 50%
2.25 = 44.44%
2.5 = 40%
2.7 = 37%
2.85=35%
3= 33.3%
3.5=28.5%
4= 25%

Those are some key numbers I memorized, but it's still like learning to speak a foreign language.

Sorry, I'm kinda slow, but is this sarcasm?

Originally posted by Blax0r

H - 42%
D - 27.57%
A - 34.42%

Last value should be 30.42%; I mis-typed my bad.