Converting Fractional and Decimal Odds

Odds on bookmakers tend to come in two forms, fractional (by default) and decimal.

Betting Exchanges on the other hand are only ever in the decimal odds format. Because of this, we need to know what the bookmaker's fractional odds are in decimal format, so that we can easily compare them with the exchange lay odds.

In each of the welcome offer step-by-step guides there is a step to show you exactly where on each bookmaker the setting is for changing their odds to decimal.

But it's also handy to know how to convert these odds manually. In this guide I will show you how to convert fractional odds to decimal odds with some really simple maths.

First lets look at each odds format individually.

Fractional Odds Format

Fractional come in the format of a fraction (like you'd see from your school days), something like:


This is 4 to 1 and means that for every £1 you bet you will get £4 profit in return if it wins (plus your stake back, so £5 total).

The best way to think about it is that if the second number was your back stake the first number is your profit. So another example:


For every £2 you place on a back bet, you win £13 profit if it wins (plus your £2 stake back for £15 total). You can also simplify the fraction by dividing the top number by the bottom to see what the profit is for every £1 placed, in this case 13/2 = 6.5/1 so £1 stake returns £6.50 profit.

Decimal Odds Format

Decimal odds have one number, followed by a decimal point and then another number, something like:


To calculate the total return from a stake when using decimal odds, simply multiply the stake by the odds. If your stake in this example was £1 then you'd get £1 x 5.0 = £5 (but unlike fractional odds this is total return, so remove the initial stake for the profit of £4).

This example of 5.0 is actually exactly the same as the fractional example of 4/1.

Converting Fractional Odds to Decimal Odds

Now that you understand the difference between the two formats, converting them should be very straight forward.

The simple calculation is you divide the first number of the fractional odds by the second number and then add one:

Fractional odds + 1 = decimal odds


4/1 (4) + 1 = 5.0

Or a little trickier:

13/2 (13 divided by 2 = 6.5) + 1 = 7.5

Another even trickier:

1/8 (0.125) + 1 = 1.125

Hope this helps explain how to convert fractional odds to decimal odds and get in touch if you have any questions at all!