Betfair Sportsbook uses both fractional and decimal odds. You can switch between the two at any time, either on:

Desktop: by selecting fractional or decimal from the black banner at the bottom of the page.
Mobile: by clicking on your balance and selecting 'Settings' and 'Odds Display'.

Betfair Exchange only uses decimal odds, but here's what some fractions look like as decimal odds:

Fractions

Whenever you see two numbers separated by a slash, i.e. 10/1, this is a fractional betting odds.

Fractional odds allow you to calculate how much money you will win on your bet compared to your stake.

Example:

9/1 for every $1 you bet, you will win $9. This can also be calculated as 1 / (9 + 1) = 0.10 - There is a 10% chance of the event happening.

1/1 for every $1 you bet, you will win $1. This can also be calculated as 1 / (1 + 1) = 0.50 - There is a 50% chance of the event happening.

1/4 for every $4 you bet, you will win $1. This can also be calculated as 4 / (4 + 1) = 0.80 - There is an 80% chance of the event happening.

 

Decimals

Whenever you see odds displayed in numerical format, i.e. 9.00, this is a decimal betting odds.

Decimal odds allow you to calculate how much money you will be returned if your bet wins. Simply multiply your stake by the decimal number shown and that is how much you will receive - including your stake.

Example:

9.00 for every R$1 you bet, you will win R$8. You will also receive your R$1 stake back, so your total return will be R$9.

2.00 for every R$1 you bet, you will win R$1. You will also receive your R$1 stake back, so your total return will be R$2.

1.25 for every R$4 you bet, you will win R$1. You will also receive your R$4 stake back, so your total return will be R$5.