Betting odds are the foundation of sports betting, determining the potential payout of a bet. Whether you're a casual punter or a matched bettor, understanding how odds work is essential for making informed decisions. In this guide, we'll break down the different types of odds, how they are calculated, and why decimal odds are the preferred choice for matched betting.
If you need to switch formats quickly while placing bets, use our odds converter to move between decimal, fractional, and American prices.
Betting odds are prices that show both your potential return and the implied chance of an outcome. Higher odds mean a bigger payout but a lower implied probability, while lower odds mean a smaller payout but a higher implied probability.
You multiply your stake by decimal odds to get your total return, including stake. The same price can be shown in fractional or American formats, but the underlying probability is the same. Matched bettors use these odds to compare bookmaker and exchange prices quickly.
Bookmakers display odds in various formats, but the most common ones in the UK and worldwide include:
Decimal odds are the simplest to understand and the preferred format for matched betting. The total payout (including the stake) is calculated by multiplying the stake by the decimal odds.
For example:
Most UK bookmakers allow users to convert odds to decimal format, and it is highly recommended to do so for ease of calculation when matched betting.
Fractional odds are commonly used in horse racing and traditional UK bookmakers. They show the profit relative to the stake—our horse racing betting guide explains where you’ll encounter them most.
For example:
Although popular, fractional odds can be harder to work with when comparing values or using matched betting tools, making decimal odds the preferred choice.
American odds are used in the US and are expressed as either positive (+) or negative (-) values—if you follow US sports like basketball, cross-check how they appear in our basketball betting guide:
For matched betting, decimal odds are best because they provide a direct payout calculation. However, if you come across fractional odds, you can easily convert them:
Decimal = (Fractional Odds) + 1
Example: 5/1 → (5 ÷ 1) + 1 = 6.00
Most UK bookmakers allow you to toggle between fractional and decimal odds in your account settings.
| Fractional | Decimal |
|---|---|
| 1/5 | 1.20 |
| 2/5 | 1.40 |
| 1/1 | 2.00 |
| 5/2 | 3.50 |
| 10/1 | 11.00 |
Bookmakers calculate odds based on probability, ensuring they maintain an edge (the overround). The process involves:
Betting odds represent the probability of an event happening and determine how much a successful bet will return.
Fractional odds show profit relative to the stake (e.g., 5/1), while decimal odds show the total return including stake (e.g., 6.00).
Use the formula: (Fractional Odds) + 1. For example, 10/3 = (10 ÷ 3) + 1 = 4.33.
Decimal odds make it easier to calculate lay bets, compare value, and use matched betting calculators.
Most UK bookmakers allow you to switch to decimal odds in your account settings.
Keep sharpening your edge by pairing this odds knowledge with our value betting framework and the step-by-step beginner sports betting guide.