What Does Odds-On Mean?

Dice with fractional odds

Whether you’re into betting or not, the phrase ‘odds-on’ is one you are no doubt somewhat familiar with. Betting-wise, an odds-on shot is something, such as a horse, that is thought to have a better than evens chance to win, but we’ll go into more detail on that later.

The phrase has also perforated general phraseology in English-speaking countries to mean that something is simply very likely to happen – i.e., “it’s odds-on I’ll end up going out on Friday!”

Odds On Meaning in Betting

The phrase, while seemingly so simple, can confuse betting neophytes. You can, of course, get the odds on something happening, for example; “what are the odds on Man City beating Liverpool on Saturday?” The hyphenated phrase ‘odds-on’ means something very different, however. To understand what ‘odds-on’ means aside from simply looking at the numbers, you’ll need to have a basic grasp of probability.

With a coin-toss, for example, taking away any weight bias or the chances of a coin landed on its side, we always think of the probability of predicting heads or tails as being 50-50. No matter what side the coin lands on, the next toss also gives you a 50-50 chance of guessing right.

If you wanted to bet on the coin toss being heads twice in a row, then you have only a one in four chance of being right, as over two coin tosses the coin could land heads-heads, tails-tails, heads-tails or tails-heads. This is why betting is never as simple as it looks. If you have a one in four chance of something happening, a bookmaker would price this up as a 3/1 shot. So, the next time you see a horse at 3/1 and believe that means it has an outstanding chance, think again! It’s never quite that easy.

If you wanted the coin tosses to produce one heads and one tails, your chances are 50-50. This is because no matter what the first toss produces, the second can either produce the result you want, or the opposite. This, therefore, is an even-money chance. An even-money chance, listed sometimes as 1/1 or 2.0 in decimal betting, is a basic 50-50 chance. Anything below that figure is described as being “odds-on”.

Net Wins, Vig & Overround

Despite the basic calculations above, an even-money shot in sports betting is never truly a 50-50 chance. That is because the bookies’ margin – what they take for themselves – has to be taken into consideration. Whenever we see a two-runner horse race and the contenders cannot be split, you never see them both with even-money odds.

Instead, they both tend to be 10/11, or odds-on, as the bookmaker needs to make something regardless of which one wins. The built-in margin in a betting market is called the ‘vig’ in North America and is known as the ‘overround’ in the UK.

How Are Odds Displayed?

Odds can be displayed in all sorts of ways. With decimal odds in pool betting, such as on the Tote, they can be displayed right to the penny. The basic fractional odds you’ll find in the UK and Ireland however move up and down in recognised increments.

Anything with a higher number first is ‘odds-against’, meaning better than even-money. A 4/1 shot therefore, if you backed it successfully, would bring you returns 4 x the amount you staked, plus your initial money back.

Any fractional odds showing the latter number being higher are odds-on. In this case, if you backed a 4/6 shot then you’d need to place £6 to ‘win’ £4, though, of course, you get your stake money back so this is still a net win. These are the basic fractions used within betting, with even-money being right between the two:

Odds Against

11/10 6/5 5/4 11/8
6/4 13/8 7/4 15/8
2/1 9/4 5/2 11/4
3/1 100/30 7/2 4/1
9/2 5/1 11/2 6/1
13/2 7/1 15/2 8/1
17/2 9/1 10/1 12/1
14/1 16/1 20/1 25/1

Odds On

10/11 5/6 4/5 8/11
4/6 8/13 4/7 8/15
1/2 4/9 2/5 4/11
1/3 30/100 2/7 1/4
2/9 1/5 2/11 1/6
2/13 1/7 1/8 1/9
1/10 1/12 1/14 1/16
1/20 1/25 1/33 1/40

Others are used, especially within football. You may see 13/10, 7/5, 8/5, etc. Simply divide the first number by the second and you have your basic calculation.

Decimal Odds

In decimal betting, the stake is included. So, a 3/1 shot on the fractional odds would read as a 4.0 shot on the decimals. This sort of betting is often more exact, especially in pool betting. You may see 2.78, 3.57, 16.38 or other random numbers used. All you need to remember is that there is a theoretical £1 stake included in that. So, an odds-on chance in decimal odds is anything less than a 2.0 shot, i.e., 1.90.

Examples of Odds On Bets

Here, Max Verstappen is 1/12 to win the F1 Drivers’ Championship. You’d need to place £12 on him to get a £1 net win.

F1 odds on example

In this football game, Arsenal are a best-priced 3/5. This equates to 0.6 to 1.

Football odds on example

On the Tote, the favourite in this horse race is £1.54, or 0.54 to 1.

Horse racing odds on example