Betfair Sportsbook uses both fractional and decimal odds, you can switch between the two at any point, either from:

Desktop: by selecting either 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 decimals odds:

Fractions

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

Fractional odds allow you to calculate how much money you will win on your bet in comparison to you stake. The number on the right(e.g. 10) is how much you will win. The number on the left is how much you need to stake.

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 that the event will happen.

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 that the event will happen.

1/4 for every £/€4 you bet, you will win £/€1. This can also be calculated as 4 / (4 + 1) = 0.80 - There is a 80% chance that the event will happen.

Decimals

Whenever you see odds displayed in numeric form i.e. 9.00, this is a decimal betting odd.

Fractional odds allow you to calculate how much money you will be returned should your bet win. Simply mutiply your stake by the decimal number shown and that is how much you will receive - including your stake.

9.00 for every £/€1 you bet, you will win £/€8. You will also receive your £/€1 stake back so your total return is £/€9.

2.00 for every £/€1 you bet, you will win £/€1. You will also receive your £/€1 stake back so your total return is £/€2.

1.25 for every £/€4 you bet, you will win £/€1. You will also receive your £/€4 stake back so your total return is £/€5.