Odds conversion functions

November 4, 2008

Odds conversion is something you will hardly ever need. For most it would be sufficient to use a conversion tables.

But if you actually need to convert odds as part of a script here is how to do so:

There are three types of odds format:

  • Fractional: 9/5 for every 5 dollars you invest you get 9 if you win and the original 5 stake.
  • Decimal: 2.8 for every dollar you invest you get 2.8 dollars, that include the original stake.
  • American: American odds are divided to two parts positives and negatives.
    Positive: 180 for every $100 you invest you win $180 and get your $100 stake back.
    Negative: -180 to win $100 you need to invest $180, so if you invest $180 and win you get $100 and the $180 stake back.

Conversion between odds is rather simple.

Given the fractional odds numerator/denominator ( for short: num/den)
The decimal odds are computed as decOdds = ((num+den)/den)
The American odds are computed as follow
if (num/den > 1 )
    usOdds = ((num/den)*100)
    usOdds = ((den/num)*(-100))