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Betting would be impossible without betting odds. Odds represent the likelihood of something happening. Everyone who starts betting eventually asks the question “how do betting odds work?”

The article explains how betting odds work, with easy-to-understand resources and down-to-earth explanations. Read this article and you will not be asking “how do betting odds work?” any longer.

What are Betting Odds and How Do Betting Odds Work in the UK?

Betting odds are a way of showing how much you’d win if the outcome of the event you’ve wagered upon is the result. Say you are betting on an EPL game, for example Brighton to beat Newcastle United. The odds of Brighton winning are 5/2. This means that if you bet £2 on Brighton, you would win £5. You would also get your £2 stake returned, so your total returns would be £7. Simple, huh?

Well, it’s not quite as simple as that, although it doesn’t get too complicated. What if you don’t want to put £2 on Brighton winning? What if the odds are 1/4? Do I have to put £4 on to win £1? The odds I’ve seen are quoted as 1.50 – what does that mean?

In our continuing quest to explain how do betting odds work UK, let’s take a look first at the three most common types of odds representation in the UK, decimal, fractional and American.

Different Types of Betting Odds Explained

Decimal Odds

Decimal odds have replaced fractional odds as the most common type of odds representation in the UK, and in particular over the past few years. They are particular popular with millennials because they struggle with fractions and prefer decimals.

To calculate potential returns with decimal odds, you just multiple the odds by your stake. In our football example above, Brighton would have decimals odds of 3.50. So a £2 stake x 3.50 = £7 return.

The main thing to remember is that decimal odds calculate your returns, not your winnings/profit. To work out how much you may win, just subtract your stake.

Also 2.00 in decimals odds is ‘evens’ in fractional odds, meaning that a successful £5 bet wins £5, and so on. Odds less than 2 mean the the selection is ‘odds on’, which means they are thought more likely to win than lose.

Fractional Odds

Before decimal odds came along, everyone in the UK used fractional odds. To calculate winnings from a bet using fractional odds, you multiply your stake by the the first or ‘top’ number (numerator) and then divide that answer by the second or ‘bottom’ number (denominator). The result is your winnings.

As we worked out above, a £2 bet on Brighton at 5/2 wins £5. £2 x 5 = £10, then divided by £2 = £5. To get your full return you need to add your stake on again.

If you see odds represented as ‘evens’ or 1/1 that means your winnings will be the same as your stake. Odds where the second number is larger than the first (i.e. 4/5) means ‘odds on’ and your winnings (but not your returns) will be less than your stake.

American Odds

Some people prefer to use the American odds format. They look complicated on the surface, but they really are not. American odds are usually a three digit number following a ‘+’ or ‘-‘ sign. The rules are as follows:

  • If the odds are positive, that’s the amount of winnings from a $100 bet.
  • If the odds are negative, that’s the amount of money you need to place to win $100.

So how do you calculate your winnings using American odds? With positive odds it’s quite simple – just divide your stake by 100 and then multiple it by the odds. So, for our continuing example, Brighton would have American odds of +250. So for a £2 bet, that’s 2/100 = 0.02 x 250 = 5. Add on your £2 stake to get your £7 returns.

Negative odds are not too taxing. In the game above let’s say Newcastle had odds of 1.40 (or fractional odds of 2/5), which in American odds would be -250. You then divide your stake by the odds, and multiple it by 100, so for a £2 stake that’s £2/250 = £0.008 x 100 = £0.80 winnings, or £2.80 returns.

Any competitor with negative American odds is odds-on. American odds of +100 count as ‘Evens’.

Different Odds Type Comparison

Type Decimal Example Fractional Example American Example
Simple (‘to one’) 11.00 10/1 +1000
Less Simple 2.75 7/4 +175
Evens 2.00 Evens, or 1/1 +100
Odds on 1.50 1/2 -200

Convert to Fractional to Decimal Betting Odds

To convert from fractional odds to decimal betting odds you just need to represent the fraction as a decimal and add one. So, with Brighton at 5/2, we need to calculate 5 divided by 2 (2.50) and add one to arrive at 3.50.

To go the other way around we need to first subtract one and then covert the decimal to a fraction. So, for Newcastle at 1.40 we subtract one to get 0.40. We now need to find a whole number that, when multiplied by our result, gives another whole number. The easiest way of doing this is by multiplying by 5 to get 2. The fractional odds are therefore 2/5 (result/multiplier).

Converting odds is perhaps best done via our bet calculator, as it doesn’t make mistakes!

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With fractional odds might be the ‘traditional’ way of expressing odds in the UK, the move over to decimal odds just … makes sense. The maths is easier, and your stake is automatically included in your calculations. Don’t be afraid to make the switch, but if you are 100 percent set on sticking with fractional odds, then that’s fine too!

The Role of Probability in Betting Odds

You may wonder how betting odds are calculated. The answer is via probability. A risk assessor is employed (or via an algorithm or AI model) by an online bookmaker will calculate the probability of a specific outcome, and then represent that outcome via the odds.

Let’s say in our example above, it it assessed that Brighton have a 25 percent chance of beating Newcastle. That means if Brighton were to play Newcastle one hundred times under current conditions, they’d win 25 times, with the other 75 games ending in a Newcastle win or a draw.

football betting odds

To get the decimal odds we just divide one by the percentage chance, which is 1 divided by 25 percent (which is 0.25) to get to 4.00. Bookies always slice a little off their odds to maintain a profit, so that’s odds of 3.50.

Betting Odds UK – a Real Example

Now, let’s look at a real example. We like BetUK for betting odds, so we looked at their site and found odds for that weekend’s big EPL game, Aston Villa v Tottenham. The odds were as follows:

  • Villa win – 13/10 or 2.30, applied probability = 43.5%
  • Draw – 13/5 or 3.60, applied probability = 27.8%
  • Spurs win – 43/20 or 3.15, applied probability = 31.7%

Those good at maths will notice that 43.5 + 27.8 + 31.7 = 103%, which some may find puzzling. The reason the combined percentages do not add up to 100 percent is because the extra three percent represent’s BetUK profit margin. This means that, if there is an even spread of money placed on all three options (which, in truth, barely ever happens), BetUK will make a profit of three percent of all money wagered.

Most UK bookies will calculate probabilities and odds with a two to four percent margin in order to increase their chances of making money on all bets placed, but this is never guaranteed as money is never spread evenly. Let’s say in our example, a total of £10,000 was bet on Villa, £2,000 on the draw and £1,000 on Spurs. Villa won, meaning that BetUK paid out a total of £13,000, but only took in £3,000, losing £10,000 in the process.

Reading Betting Odds: What the Numbers Mean for UK Sports Bettors

The way to beat the bookies is to compare your thoughts on the chance of something happening to the odds given by the bookie. Say, in our real example, you think there is a 40 percent chance of Villa drawing with Tottenham. The bookies applied probability is 27.8 percent, giving you an 12.2 percentage advantage meaning you feel this is a value bet.

Conversely, you think Villa have a 30 percent chance of winning. The implied probability given by the bookie is 43.5 percent, giving them the odds advantage (13.5 percent). This would not then be the bet for you.

Remember, to covert decimal odds to applied probabilities, just divide one by the odds. Then compare your thoughts to the probability applied by the bookie.

How to Choose the Right Betting Odds: Tips and Strategies for UK Bettors

Getting things right when it comes to betting odds is key to maximising your profits when betting on sports. Here are three top tips which will help you in your sports betting experiences:

  • Make sure you do your research: No matter the sport, the more you know about it, the more likely you are to make consistent profits. Don’t bet on something you just have ‘a hunch’ about.
  • Shop around for the most competitive odds: Different bookies in the UK offer different odds (although the variations are really not that drastic). It pays to make occasional comparisons concerning odds, and pick the bookies that consistently offer the best prices.
  • Consider the implied probability: Always consider the implied probability when choosing betting odds. If you believe the actual probability of an event happening is greater than the implied probability, the odds may be a good value bet.

Common Mistakes to Avoid When Using Betting Odds in the UK

Betting is not a perfect activity but you can reduce your chances of losing money if you try and avoid making mistakes. We’ve listed three common mistakes made when using odds, so that you can eradicate them from your betting procedure.

  • Ignoring the implied probability: Make sure you consider the implied probability when selecting the most beneficial betting odds. If the implied probability is too high, the odds may not be a good value bet.
  • Chasing losses: Don’t try to chase losses by placing bigger bets. The likelihood is that this will only lead to further losses. Just remember, everyone has a bad streak from time to time.
  • Remember the difference between profits and returns. When using fractional or American odds, the calculation gives your profits. When using decimal odds, the calculation gives your returns.

UK Bookies with the Best Odds

Of course, we would not be betting sites experts if we did not know which UK betting sites offered the most consistent and competitive odds. Here now are three bookies that we recommend for the consistency of their beneficial betting prices:

  • BetUK – Bet £10, Get £30 In Free Bets
  • Spreadex – Get £50 In Bonuses
  • BeeZeeBet – Bet £10 Get £10 Free Bet
  • 10Bet  – 100% First Deposit Bonus Up To £50
  • Betfred – Bet £10 Get £40 In Bonuses

Wrapping Up

Understanding how betting odds work is essential if you want to make informed betting decisions in the UK gambling industry. As you’ll be aware, there are three main options of odds display at online UK bookies – fractional, decimal and American. Which you prefer is your choice, and most sites will allow you to pick which format you want to use.

We hope this page has answered your question ‘how do betting odds work?’, and you are now in pole position to make the best decisions possible in terms of sports betting and in line with your understanding of how do betting odds work UK.


How do betting odds work in the UK?

The betting odds represent the potential payout from any bet in the UK, based on the probability of the event occurring. The longer the odds (i.e. the bigger the potential payout), the less likely the outcome. Odds come in three formats: fractional (i.e. 5/2), decimal (3.50) and American (+250). There are many other formats, but these are the three most common ones found at UK bookmakers.

How do you work out betting odds?

Betting odds are typically expressed as fractions, decimals, or American odds. To convert between them, you can use conversion calculators or formulas. For fractional odds, divide the first number by the second number and add one. For decimal odds, multiply the stake by the odds and subtract the stake. If you're using American odds, divide the odds by 100 and multiply by the stake.

How do sports betting odds work?

Bookies make an assessment of the probability of an event occurring. They then add on a small percentage to increase their chances of making a profit, and then convert that percentage to odds. You can convert back yourself by dividing one by the odds (in decimal format). For example, odds of 3.50 represent a probability of 29.4%.

How do odds work in football betting?

All football matches with have three sets of odds – the odds for a home win, the odds for a draw, and the odds for an away win. You can calculate the probabilities of each outcome using the method in the previous question, then compare them to your own thoughts or calculations. If you think an outcome has a greater probability than the odds imply, then that is a value bet.

How do American betting odds work?

American betting odds can be positive or negative. Positive odds represent the amount of money won for a $100 bet. Negative odds represent the amount of money need to be bet in order to win $100.

Peter Addison
Peter Addison
Peter Addison

Peter joined the team in 2023, having previously worked for many high-profile gambling-related sites such as RightCasino, JustSlots, WhichBingo and An experienced head when it comes to all aspects of iGaming, Peter is a fanatic fan of sport, including football and US sports such as baseball and American football. He is also a multi-published fiction writer, although sadly, not a wealthy one.

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