Betting odds explained

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How do betting odds work?

What are odds?

Odds are a way of showing 1) how likely something is to happen and 2) how much you'll win if it does happen.

How are odds shown?

Odds can be shown in different ways. In betting, the main forms of odds you'll see are:

FRACTIONAL ODDS e.g. 7-1 (as used by bookmakers)
DECIMAL ODDS e.g. 11.0 (used on betting exchanges)
MONEYLINE ODDS e.g. +120 (used by American sportsbooks)
PERCENTAGE ODDS e.g. 25% (shown as payouts in casino games)

To explain odds, we'll answer the two most important questions

What are the chances of it happening AND How much will I win if it does?

What are the odds of it happening?

If you choose a card at random from a standard pack (13 cards of 4 suits, no jokers), what are the chances of selecting a diamond?

There are 13 diamonds and 52 cards. So the chance of choosing a diamond is 13 chances out of 52 i.e. 1 in 4.

The easiest way to show this is as a FRACTION i.e. 1 / 4 - there are four possible outcomes and only 1 of them is a winner.

Another way to show this is as a PROBABILITY. Probability ranges from 0 (impossible) to 1 (certain). The card bet above would be shown as 0.25.

Bookmakers odds

In bookmakers odds, this would be shown as 3-1. You might think it would be 4-1. It isn't, because bookies odds show the chances against the event. As there are 3 cases where this bet won't win and 1 where it will, the odds are 3-1.

Decimal odds

In decimal odds, this bet would show as 4.0. Remember, in decimal odds, the number shown is the payout, not just the winnings. A £1 bet on this result would give you £4 (£3 winnings plus your £1 stake)

American odds

In tems of a moneyline, this bet would be shown as +300.

Percentage odds

In percentage odds, this bet would be shown as a 25% chance.

How much will I win?

Bookmakers odds (Fractional)

Bookies odds (also known as Fractional odds) are shown as A-B or A/B i.e. 'For every B units you bet, you will win A units' (We'll call A the 'return' and B the 'stake') eg

3-1 : every 1 unit you stake will return 3 units
7-2 : every 2 units you stake will return 7 units
9-4 : every 4 units you stake will return 9 units.

Your stake is returned with your winnings, so your payout (ie the money you're given) is A / B x stake + stake

eg if you bet £100 on a horse whose odds are 9-4, your overall payout on a winning bet is 9 / 4 x 100 + 100 = £325

You'll sometimes hear of an 'Odds on' favourite. What this means is that the event is so likely to happen that the bookies have set the odds so that the return is less than the stake.

For example:

1-2 (or 2-1 ON) means you get 1 unit for every 2 staked
2-7 (or 7-2 ON) means you get 2 units for every 7 staked

Don't forget, though, that your original bet is still returned, so you still win overall.

Eg a £100 bet on a horse at 1-2 pays out £150 (1 / 2 x 100 + 100).

If this seems a bit confusing, try our Instant Bet Calculator and work out your winnings!

We've also included a section on different bet types (each-way, place and multiple (Yankee, Lucky 15 etc)

Decimal odds

Decimal odds are the favoured method of displaying odds on betting exchanges such as betfair. With decimal odds, things are simpler as the figure quoted is the payout per unit staked. For example, for a £100 bet at betfair,

7.0 pays out £700 (7.0 x £100 staked)
4.1 pays out £410 (4.1 x £100)
1.2 pays out £120 (1.2 x £100)

Remember, though, the great thing about betfair is that it's an exchange (see our guide to betting exchanges). As such, betfair are not an ordinary bookmaker - they don't set the odds. They allow bettors to choose whether to back or lay on an event, so you're effectively trying to outwit other punters. Great fun and very profitable if you know what you're doing. To help you get familiar with the exchange, they'll give you free £25 bet when you open your account.

American odds

American sportsbooks have a slightly different way of showing odds, which is known as a moneyline. It's very often used in NFL matches, for example, where one team is the favourite and one is the underdog. For example, you may see the following betting options for a match:

Chicago Bears -140
Dallas Cowboys +110

Moneyline odds are shown in two ways - the favourite as a negative number, the underdog as a positive.

If the figure quoted is positive, the odds show how much you'd win on a $100 wager. Positive numbers are the same as Odds Against.

If the figure quoted is negative, the odds show how much you'd need to wager in order to win $100. Negative numbers are the same as Odds On.

For a comparison of moneyline odds versus fractional and decimal, see the table below.

Percentage odds

Percentage odds are an accurate way of showing how likely something is to happen (see below).

Asian sportsbooks such as 138 will use probability when quoting sports betting odds, but you'll most likely come across percentage odds when playing at casinos.

Casinos use percentages to show the odds of individual bets in a game, plus the overall payout rate for the casino. The closer the payout is to 100%, the more likely you are to win.

What will I win?

To see how much you will win for stakes of £1, £5 and £10, for each of the betting odds discussed above, have a look at our Betting odds comparison table (below) or simply use our Instant Bet Calculator.

Betting odds comparison table

Fractional Decimal American % Probability Returns (£1) Returns (£5) Returns (£10)
Odds On
1/2 1.50 -200 67 0.67 £1.50 £7.50 £15.00
8/15 1.53 -187.5 65 0.65 £1.53 £7.65 £15.30
4/7 1.57 -175 64 0.64 £1.57 £7.85 £15.70
8/13 1.62 -162.5 62 0.62 £1.62 £8.10 £16.20
4/6 1.67 -150 60 0.60 £1.67 £8.35 £16.70
8/11 1.72 -137.5 58 0.58 £1.72 £8.60 £17.20
4/5 1.80 -125 56 0.56 £1.80 £9.00 £18.00
5/6 1.83 -120 55 0.55 £1.83 £9.15 £18.30
10/11 1.91 -110 52 0.52 £1.91 £9.55 £19.10
Odds Against
Evens 2.00 +100 50 0.50 £2.00 £10.00 £20.00
11/10 2.10 +110 48 0.48 £2.10 £10.50 £21.00
6/5 2.20 +120 45 0.45 £2.20 £11.00 £22.00
5/4 2.25 +125 44 0.44 £2.25 £11.25 £22.50
11/8 2.37 +137.5 42 0.42 £2.37 £11.85 £23.70
6/4 2.50 +150 40 0.40 £2.50 £12.50 £25.00
13/8 2.63 +162.5 38 0.38 £2.63 £13.15 £26.30
7/4 2.75 +175 36 0.36 £2.75 £13.75 £27.50
15/8 2.83 +187.5 35 0.35 £2.83 £14.15 £28.30
2/1 3.00 +200 33 0.33 £3.00 £15.00 £30.00
85/40 3.13 +212.5 32 0.32 £3.13 £15.65 £31.30
9/4 3.25 +225 31 0.31 £3.25 £16.25 £32.50
5/2 3.50 +250 29 0.29 £3.50 £17.50 £35.00
11/4 3.75 +275 27 0.27 £3.75 £18.75 £37.50
3/1 4.00 +300 25 0.25 £4.00 £20.00 £40.00
100/30 4.33 +333 23 0.23 £4.33 £21.67 £43.33
7/2 4.50 +350 22 0.22 £4.50 £22.50 £45.00
4/1 5.00 +400 20 0.20 £5.00 £25.00 £50.00
9/2 5.50 +450 18 0.18 £5.50 £27.50 £55.00

To work out exactly how much you'll win on your bet, use our Instant Bet Calculator

Why Bookies odds aren't accurate

The problem people have in understanding odds is trying to link the bookies' odds of a horse winning with its actual chances of winning. This is because bookies' odds are influenced by probability, but are not an accurate representation.

Bookmakers set their prices with two intentions: firstly, to attract money for outsiders; secondly, to minimise their losses should the predicted winner win.

Unlike the fraction examples given above, betting on a horse at evens does not mean that it has a 50% chance of winning. Remember that the bookie has set those prices.

The 'rake' for bookmakers - i.e. the amount of profit they expect on their takings - is around 25%. In other words, their payout percentage is around 75.

The advantage of bookies odds

The advantage with Bookies is that in most races the favourite will generally set off with odds better than 1 to 1. For example, in a race like the Grand National, the favourite - i.e. the horse most likely to win (in the bookies' opinions) - will often pay out at 9-1.

Casino games and sports betting are different propositions and the odds and payouts are calculated very differently. Remember that casino games have very few variables - the results always occur within predictable ranges.

With horse racing, lots of factors can affect the result; the weather or an illness to horse or jockey could have a major bearing on the outcome.

Successful sports betting

The key to successful sports betting is to understand that whereas casino betting is an exact science - a battle against long-term probability - betting on horses is far more random.

Bookies try their best to ensure they don't lose - and in the main they don't.

But those random factors will always throw up the opportunity for a good return on your bet. Successful punters know how to read the market and see where the odds don't quite match up to the likely outcome.

Fancy a flutter?

Now you know all about odds, why not try out your new-found skill with a little wager? To help you on your way, we've linked up with a few online bookies, all of which are happy to offer you FREE bets - up to £200 in some cases.

Check out the latest offers on our latest bookies promotions page.

How to get the best prices

Ante Post betting is betting in advance of the start of an event. Bookmakers are keen to price up major sporting events much earlier than the actual start date.

In the case of the Grand National, punters can bet on the race a year before it is due to be run. In fact, prices are available immediately after the race for the following year's race!

This is because bookies want to generate revenue as early as possible, by offering odds that would seem incredible on the day of the race. For example, Aurora's Encore (the 2013 Grand National winner) was available at over 200 to 1 just a few months before the race.

If you take your time to research the trainers, the horses and the races, you can find excellent value by betting ante post.

The best ante post bookmaker

Leading the way in ante post betting is betfair. betfair are the first to put up ante post prices for major events and offer very competitive odds.

As they have a strong focus on Horse Racing and Greyhound Racing, they can cover 14 countries worldwide, including the USA and Canada.

For the best in ante post betting, check out betfair.