Fractional odds vs. Decimal odds


There are three main odds formats available to bettors; Fractional odds, Decimal odds and American odds. Fractional odds have historically been used in the UK but Decimal odds are arguably the most popular format. How do you convert Fractional odds into Decimal or American? Read on to find out.

It might be obvious to most bettors but regardless of which odds format you use for a bet, the potential profit will always be the same – it is just how these odds are presented that differs.

Fractional odds, unsurprisingly, are displayed as fractions. American odds use a unique + and – system and Decimal odds, as you may have guessed, are displayed as decimals – the key difference is that Decimal odds always include the stake.

You can use our helpful bet calculator to work out the potential profit and return of your bet in any odds format, but knowing how to work this out for yourself is a critical part of understanding how odds work and ultimately, being able to calculate expected value.

Fractional odds to Decimal odds conversion

Converting Fractional odds into Decimal odds is fairly straightforward. Simply turn the fractional number into a decimal number by turning the fraction into its decimal equivalent and then, crucially, add one.

Here’s an example of how to convert Fractional odds into Decimal odds:

Numerator / denominator + 1 = Decimal odds

5/2 = 5/2 + 1 = 3.5

Decimal odds to Fractional odds conversion

If you are more comfortable with Fractional odds you can convert Decimal odds by reversing the formula above:

Decimal odds -1 and converted into a fraction = Fractional odds

3.5 – 1 = 2.5 which as a mixed fraction is 21/2 but in its more common improper form is 5/2.

Odds conversion chart

Fractional Decimal American
1/5 1.2 -500
2/9 1.22 -450
1/4 1.25 -400
2/7 1.29 -350
3/10 1.3 -333.3
1/3 1.33 -300
4/11 1.36 -275
4/9 1.44 -225
1/2 1.50 -200
4/7 1.57 -175
4/6 1.66 -150
4/5 1.80 -125
1/1 2.00 -100
5/4 2.25 +125
11/8 2.38 +137.5
7/4 2.75 +175
2/1 3.00 +200
9/4 3.25 +225
5/2 3.50 +250
3/1 4.00 +300
7/2 4.50 +350
5/1 6.00 +500
10/1 11.00 +1000
20/1 21.00 +2000
50/1 51.00 +5000
100/1 101.00 +10000
1000/1 1001.00 +100000

Looking for odds that aren’t included in the odds conversion chart? Use Pinnacle’s odds converter.

Calculating profits with Fractional odds

Fractional odds originated within horse racing as a way to represent the return on the underlying probability. They shouldn‘t be confused with ratios. Although 3/1 or “three to one” make it easy for bettors to understand their profit in relation to the stake – your return is three times your stake – the more accurate and precise the odds are, the more complicated things become.

Fractional odds

Odds expression (most commonly used in the UK) which presents odds in a fractional format.

The easiest way to calculate profits using Fractional odds is to view the fraction as Profit/Stake – so a $1 bet at 5/1 would result in $5 profit. However, the odds can be unfamiliar fractions (proper and improper) and your stake might not always be a whole number so the following equation should be used:

Returns = (Stake / denominator) x numerator) + stake

So if we use a $15 bet at odds of 5/2, the calculation would be as follows:

Returns = ((15 / 2) x 5) + 15 = 52.50

Calculating profits with Decimal odds

Decimal odds have become increasingly popular in recent years. Bettors are beginning to favour the simple, more accurate Decimal representation of a bet’s potential return, which includes the stake amount.

Decimal odds

An odds expression (sometimes referred to as European odds) where the odds are shown in decimal format.

In order to calculate the return of a bet with Decimal odds, all you have to do is multiply your stake by the Decimal odds offered:

Stake x odds = returns

Therefore, a $10 bet at odds of 3.5 would return $35.

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