Fractional odds which are also known as British odds are popular in the betting industry and are used by some of the biggest bookmakers in the world. Fractional odds are typically written with a slash (/)” or a “hyphen (-), for example, 4/1 or 4-1. 4/1 (four-to-one) odds would mean that you win $4 against every $1 you wager, in addition to receiving your dollar back (i.e., the amount you wagered). So if your bet wins, you will receive a total of $7.
How to convert American odds to fractional odds
The American odds with a + sign simply show how much money you would make for every $100 you bet, excluding your original stake of $100. In order for you to covert American odds into the fractional odds you simply have to divide the expected profit by 100 and then multiply by 10
For example (150/100 = 1.5/1)
1.5 x 10 15/10.