Odds can be displayed in two ways: Fractions or Decimals
You will probably be most familiar with odds as fractions (e.g. 3/1). However, you can choose to display them as decimals (e.g. 4.00) if you wish.
Below is a table highlighting the difference between the two:
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 left(e.g. 10) is how much you will win. The number on the right is how much you need to stake.
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.
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.
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.
Decimal odds allow you to calculate how much money you will be returned should your bet win. Simply multiply your stake by the decimal number shown and that is how much you will receive - including your stake. The decimal odds are displayed up to 2 decimal places, but the return will be paid out by calculating at the actual odds, to the nearest £/€ 0.01. For example, if your bet is placed at odds of 4.3333333 (this is 10/3 in fractional), a £/€ 10 bet would return £/€ 43.33 if it wins, but your odds would show as 4.33.
for every £/€1 you bet, you will win £/€8. You will also receive your £/€1 stake back so your total return is £/€9.
for every £/€1 you bet, you will win £/€1. You will also receive your £/€1 stake back so your total return is £/€2.
for every £/€4 you bet, you will win £/€1. You will also receive your £/€4 stake back so your total return is £/€5.