How to convert between Decimal and US Odds

[Landprofits]

I've noticed that a few people are choosing decimal odds at US facing books and a few discussions are taking place with one person talking decimal and someone else talking American, so I thought it would be helpful to point out how to convert between the two.

First of all there is a calculator here;

The Gambling Times | Bookmakers, Reviewed By The Gambling Times | Claim Cashback

And also a table of commonly used odds here;

The Gambling Times | Odds Conversion Tool

I do think it's a good idea to know how it's done though, and with that in mind;

1) The simple one first. If the odds are positive, divide the odds by 100. Then add 1. So +450/100 = 4.5........ then add 1 to that total to get decimal odds off 5.5. Do a few for yourself and you will see that you don't have to be a genius to work out that, as long as the odds are positve, just knock the zero off, stick the decimal point in there and add one. Actually to quote this correctly I should say move the decimal point 2 places to the left and add one.

+350 becomes 4.5
+780 becomes 8.8
+1200 becomes 13.0

2) If the odds are negative, you divide 100 by the odds then add one. Knock the (-) sign off before you do that calculation though.

Thus, -120 is 100 divided by 120 = 0.83, and finally add 1 to that to get 1.83.

-145 becomes 1.69
etc..
etc....

[munk]

Nice one LP.

Worth maybe quoting some info I posted on the difference between risk/win at US books which is all part and parcel of american odds:

The US books operate on a Risk/Win basis - you risk $x to win $y. The +y numbers indicate risking $100 to win $y dollars (ie if you bet on a line that's +110, you risk losing $100 to win $110), whereas the -y odds indicate risking $y to win $100 (ie if you bet on a line that's -110, you risk $110 to win $110). 'Risk' can be swapped with 'Stake' here in traditional EU/UK 'notation', you 'risk' losing your stake if your bet loses.

To be fair I wouldn't (didn't) understand this (fully) until I'd played a little, you have to place a few bets to understand it... also try and think about how the US odds system works:

To convert +(US ODDS): DECIMAL ODDS = (+US ODDS / 100) + 1
ie: +110 US is the same as decimal (110/100) + 1 = 1.1 +1 = 2.1

To convert -(US ODDS) = (100 / -US ODDS) + 1
ie -110 US is the same as decimal (100/110) + 1 = 0.91 + 1 = 1.91

(note if you add these US decimal odds up they equal 1... +110 -110 = 0 - also if you add them up in EU notation they also equal 1 - to do this you need to add the sum of the reciprocals of the odds, which is 1/2.1 + 1/1.91 = 0.99975 = 1.... you can see why working in US odds is easier! Note this is a 'no juice' bet, the bookmakers make no 'juice' from you).

Not really that obvious until you play with it and have money riding on it!

Also a simple (and fairly obvious I suppose!) trick I use to convert negative US odds into decimal - take the negative number, divide by 100 in your head, find the reciprocal and add one. To be fair that's exactly what LP said above and what I quoted above... BUT the neat 'trick' is the way you can do it in windows:

1. Do 123/100 in head (ie 1.23).
2. Hit 'windows+r' to open the run box.
3. Type in 'calc' and hit enter (opens up MS calc).
4. Type in '1.23 r' (this calculates the reciprocal of 1.23, which is 0.81)
5. Add 1 in your head (ie 1.81)

This way you know -123 is equivalent to 1.81 decimal. Takes about 5 seconds if you have 'calc' on a hotkey or tend to keep calc running in the background.

Another small 'tip' is that for a small negative number 'x' (say x less than 110), the decimal equivalent is roughly equal to 3-(x/100). So for -110, the decimal equivalent will be very roughly equal to 3-1.1=1.9 (is actually 1.9). The further away from evens you go the poorer the approximation.

[nixonite]

I always try to use US odds when I'm dutching. Makes finding arbs so much easier (IMO).

Although this may have been discussed (or obvious) from the above 2 posts, it is an arb if the two totals are positive (e.g. +110 and -109), no loss if equal (e.g. +110 and -110) and a loss if negative (e.g. +109 and -110).

[KingColly]

For anyone who uses Ultimatcher, or similar spread-sheets, and wants to enter odds in US format (to then be converted into decimal format by the sheet), the formula is as below.

=IF(E18>0,1+E18/100,1-100/E18)

(assuming E18 is where the US odds have been entered)

I recently modified one of the bet matching tabs in Ultimatcher to accept US odds, using this formula.

Hopefully that is of use to somebody!

[Landprofits]

For anyone who uses Ultimatcher, or similar spread-sheets, and wants to enter odds in US format (to then be converted into decimal format by the sheet), the formula is as below.

=IF(E18>0,1+E18/100,1-100/E18)

(assuming E18 is where the US odds have been entered)

I recently modified one of the bet matching tabs in Ultimatcher to accept US odds, using this formula.

Hopefully that is of use to somebody!

KC do I take it you enter that formula in one of the dutching tabs, leaving the original untouched?

[KingColly]

Well my Ultimatcher (V2) has 3 bet matching tabs.

I have modified the tab listed as "bet matching 3".

I replaced the formula in D18 with

=IF(D17>0,1+D17/100,1-100/D17)

I replaced the formula in L18 with

=IF(L17>0,1+L17/100,1-100/L17).

I am not really an Excel whiz, but it seems to be doing the trick for me thus far.

[munk]

On a similar note, these are formulae for calculating the 'break even' odds in american and decimal odds required for a given decimal odds:

=IF(A1="","",1/(1-1/A1))
(for displaying in decimal what the 'break even' odds are)

=IF(A1="","",IF(A1<2, "-"&(1/(A1-1))*100,"+"&(A1-1)*100))
(for displaying in american odds what the 'break even' odds are)

So if you have say '3' in cell A1, and the two formulae above in cells B1 and C1, B1 and C1 would read '+200' and '1.5' to show that the break even odds for '3' are +200 in american odds format or 1.5 in decimal (so you know anything you find over +200 / 1.5 will be profitable).

Makes it a bit easier to see at a glance what kind of odds you're looking at to at least break even.