Betting Odds Explained

odds explainedIf you have only ever bet with UK bookies then the only odds format you might be familiar with are fractional odds. Modern betting, especially online, is however now a global affair and depending on who you bet with it is now common to see other odds formats including decimal odds, percentage odds, proportional odds and American Odds (referred to as moneyline).

Betting companies based in Europe in particular will generally provide odds in decimal format by default, and this can make calculating fixed odds prices a little difficult to the uninitiated.  Even with UK bookmakers many bets are represented as decimals, such as most handicap markets.  Not to worry, in this article we explain the difference between odds systems and how to calculate, compare and convert fixed odds winnings using any format.

Odds Format Comparison and Conversion Table

FractionalDecimalAmerican% Return (-stake)% to break even
100/1 101.0 10,000 10,000.00% 0.99%
9/1 10.0 900 900% 10%
4/1 5.0 400 400% 20%
3/1 4.0 300 300% 25%
2/1 3.0 200 200% 33.33%
Evens (1/1) 2.0 100 100% 50%
1/2 1.50 -200 50% 66.67%
1/3 1.33 -300 33.33% 75%
1/4 1.25 -400 25% 80%
1/9 1.11 -900 11.11% 90%
1/100 1.01 -10,000 1.0% 99.01%

Types Of Fixed Odds Formats

Quick Reference

By treating the amount you can win as 'Z' we can easily summarise different odds types.

  • Fractional Odds - the number on the left displays the amount you can win from a given stake (Z).
  • Decimal Odds - display the amount you can win from a stake of one unit stake, plus your stake (Z + 1).
  • American Odds - positive odds are simply multiples of 100 (Z x 100), negative odds are division of 100 (100 / Z).

Fractional Odds

betting oddsThis format is most familiar in the UK and Ireland and continues represents the most common format. At the end of the day if we haven't given up miles, yards, feet and inches yet in the UK so it will be a long time until we switch to decimal odds as default. Think of a betting shop window, have you ever seen anything but fractions?

The fraction is a mathematical representation of the amount a punter can win (first number) versus the amount they need to stake to win that amount (second number). Therefore 4/1 means you for every £4 you want to win you need to stake £1. The first number represents what you will win excluding your stake, so if you were to place a £1 bet at 4/1 you would win £5 but also get your £1 stake back giving you total returns of £5 if the bet win (£4 winnings + £1 stake).

Fractional odds must always be whole numbers. If potential winning are not divisible by 1 as a whole number then the stake unit increases to the closest whole number representation. If you had a price of 3.5/1 it cannot be written this way so in this instance it becomes 7/2, this is the closest whole number derivative of that price. In the case of a price that was say 3.3333/1 this would be represented as 10/3 and so on, see odds table above.

If something is odds-on it means for each unit you stake you will receive less than one unit back in winnings. In the instance of 1/4 for example for each £1 you want to win you need to stake £4. If your winnings are equal to your stake then the odds are 1/1 but this is commonly referred to as Evens.

fractional odds format

When betting on an each-way price for example you will often need to work out your own each way odds. If you back a horse at 12/1 each-way at one quarter of the total odds and the horse were to place the place part of the bet would be paid out at 12/4 or 3/1.

I like to think of fractional odds like bet you would place with your mate where you don't actually part with your stake. For 4/1, you say if you win I will give you £1 but if I win you give me £4.

Decimal Odds

Decimal OddsThe favoured odds format in Europe, Australia, New Zealand and Canada. Effectively anywhere where you drive in kilometres per hour bookies will use decimal odds. Luckily decimal odds are not too hard to understand and once you have encountered them a few times it is easy to convert from decimal to fraction (or vice versa) in your head.

The decimal represents the amount you would win including getting your stake back. 4/1 in fraction therefore now become 5.0 in decimal, here you are staking £1 and getting returns of £5, your winnings are still £4 it's just that the price included getting your stake back.

Taking the example from fractional odds above for decimal odds you are having a bet but giving your stake away. For 5.0, you say I will give you £1 now but if I win you give me £5 back.

The equivalent of evens (1/1) in decimal is 2.0 this is one unit stake and one unit winnings (1+1=2). A line that is odds-on in decimal format will always be a decimal of 1, so for example 1/4 (£4 stake for every £1 won) in decimal would be 1.25.

If you want to a quick way to work out your winnings in decimal format simply multiply what you want to stake by the decimal. For example if you stake £5 at 3.0 (2/1) then multiply 5 x 3.0 giving returns of £15. If this were odds on, say 1.40 (2/5) multiple 5 x 1.4 this gives £7 returns, etc.

decimal odds format

In the case of an each way bet with decimal odds, using the previous of a 12/1 horse this would be 13.0 in decimal. If you back this each-way and it places at one quarter the odds unlike fractional you can't just divide the winning odds by 4. First subtract the stake (13-1) then divide by 4 (12/4 = 3) and add the stake back (3+1=4). The decimal odds for the place would therefore be 4.0 (3/1).

Decimal odds tend to be favoured by betting exchanges such as Betfair and in index, financial and spread betting.

American (Moneyline) Odds

As it says on the tin these odds are favoured in America and are a little different to fractional and decimal odds as these can be both positive and negative numbers.

american odds format

Positive American Prices

If a betting line is favourable (i.e. you can win more than one unit per one unit stakes) then American odds are positive. This tells you how much money will be won for each £100 wagered. If a money line shows +400 this means for every £100 stakes you will win £400, this is equivalent to 4/1 in fractional or 5.0 in decimal.

Negative American Prices

Conversely if the odds are unfavourable (odds-on, i.e. for each one unit stakes you will win less than one unit) then American odds are displayed negatively. This time the moneyline quotes the amount that must be wagered to win £100. In this instance if the American odds are showing -400, meaning you must stake £400 for each £100 winnings, this is equivalent to 1/4 in fractional or 1.25 in decimal.

Percentage and Proportional Odds

It is rare to see but occasionally you may see your chances of winning represented as a percentage. These are not odds prices as such but instead show the percentage of winnings relative to stake or the percentage of times you need to win to break even. A proportion is just a percentage divided by 100.

Percentage win for a 4/1 bet would therefore be 400%, meaning you will win 400% of your stake (very similar to positive American Odds). Conversely an odds-on line like 1/4 would be 25% winnings relative to stake.

The percentage win to break even represents the number of times a bet at those odds would need to win so that you didn't lose overall. Taking our consistent example of 4/1 you would need to win 20% of the time to break even. An odds-on line such as 1/4 would need to win 80% of the time to break even. For more see the table at the top of this page.