Written by Luke Bradshaw Lee Fact Checked by Sam Darkens Updated June2026 Ranks in OLBG’s Top 10s more than any bookmaker Competitive Odds and Range of Betting Options The no.1 app across all UK bookies Ranks in Top 10 for 11 different categories Imaginative bonuses and offers across different sports Top three bookie for in-play betting Ranks in Top 10 for seven
This percentage is not the profit but the amount wagered. For example, a bettor wages £10 with the odds at 1.20. 1.20 * 100 = 120% £10 * 120% = £12 The bettor wins 120% of their original wager back with a successful bet. To convert decimal odds to a probability you need to take into account the value of the decimal. Odds of 2.00 is the same as a 50% chance of winning.
Odds above 2.00 has a lower than 50% chance of winning and vice versa. To turn decimal odds into probability, use the formula 100/odds. For example, if the team’s odds of winning is 6.00, the probability of them winning is 100/6, which equals 16.7%. Always remember that the odds displayed and offered by bookies are always probability based and should never be interpreted as a guarantee that a certain event will happen. Use what you have learnt and Check out William Hill’s latest sports betting odds.
American odds are also called money line or US odds. These are the odds format primarily used in the US and will rarely get adopted by bookmakers from the United Kingdom. They can be confusing compared to fractional or decimal odds until you have got the hang of them. They are displayed with either a positive or minus number: A positive number indicates how much profit you will get if you bet £100. Indicates what you must bet to bet betting promo codes for existing customers make £100 profit. different categories Ranks in Top 10 for four different categories Ranks in Top 10 for four different categories No.2 bookie for Politics, and Entertainment/Specials betting Ranks in Top 10 for horse racing and BOG Independently Owned Betting Service for 20 years Excellent in-play betting and price boosts Football Early Payout, Acca Boosts and more No.1 bookie in the country for Best Odds Guaranteed.
Lots of promotions and Best Odds Guaranteed Only bookie in the UK with markets on specific Welsh events Decent in-play graphics, particularly for football, tennis and basketball.
To convert fractional odds to percentages, use the formula (x / y) * 100 with x/y representing the fraction. A bet of £10 with the odds 7/3. Add the wager to the won amount = £33.33 return. When presented with fractional odds, it can sometimes be very easy to determine the probability of an occurrence, but at other times it might not be so simple. Knowing the probability of an outcome can be essential to bettors who are perhaps not as well informed on a certain event, so if you want to put a bet down but would like to understand how likely the outcome is with data and a fixed probability, use the formula (y / (x + y)) * 100 where odds equal x/y.
Odds: 3/1 (1 / (3 + 1)) * 100 (1 / 4) * 100 0.25 * 100 25% probability of winning Odds: 7/3 (3 / (7 + 3)) * 100 (3 / 10) * 100 0.3 * 100 30% probability of winning Odds 1/1 (1 / (1 + 1)) * 100 (1 / 2) * 100 0.5 * 100 50% probability of winning which is why odds of 1/1 is called “evens”. It is always worth considering that the odds displayed and offered by bookies are always probability based and can never be made as a guarantee that a certain event will happen. Now that you have a good understanding of fractional odds and probability and are ready to start weighing up individual bets. William Hill provides unmatched betting odds across sports, television, politics and more. Another format of odds that is popular among punters is decimal odds.
Decimal odds use a decimal format to display the stakes and are usually utilised for a quick view of the probability of an event. Decimal odds also make it easier for punters to compare odds without complicated mathematical formulas and allow for a quick view of potential winnings. The higher the number, the higher the potential winnings. The William Hill website allows bettors to choose between their preferred odds format, be that decimal or fractional. To work out winnings, you need to multiply the stakes by the odds: 2.00: Bet £3, win £6 (equivalent to 1/1 evens) To calculate the winning percentage when betting with decimal odds, multiply the decimal by 100 to get the percentage. No.3 bookie in the country for tennis betting 'Book a Bet' and 'Combo Boost' Features No.1 bookie for darts and boxing Ranks in Top 10 for 16 different categories.
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| Model | How It Works | Example Platform | User Cost |
|---|---|---|---|
| Affiliate Commission (CPA) | Earns fee for each referred user who signs up/deposits. | Oddschecker | Free |
| Subscription Tier | Premium features (e.g., no ads, advanced tools) for a monthly fee. | BettingExpert Pro | $19.99/month |
| Display Advertising | Sells banner and native ad space to bookmakers. | Many free apps | Free |
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| Sport | Common Match Markets | Special/Prop Markets |
|---|---|---|
| Football (Soccer) | 1X2, Over/Under, Both Teams to Score | Anytime Goalscorer, Correct Score |
| Tennis | Match Winner, Set Betting | Total Games, Ace Count |
| Basketball (NBA) | Moneyline, Point Spread, Totals | Player Points, Quarter Winner |
| Horse Racing | Win, Each-Way, Place | Forecast, Tricast |
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On mobile, this is located at the bottom of the menu. To convert decimal odds to fractional odds use the formula (x – 1.00) and place over 1. For example: 6.00 odds 6.00 – 1.00 = 5.00 = 5/1 You may need to simplify the fraction like this more complicated example. 5.50 odds 5.50 – 1.00 = 5.5/1 = 11/2 To convert decimal odds to American odds, you will need to determine which formula you use based on the decimal value. For decimal odds 2.00 or greater use the formula (decimal odds – 1) * 100.
Example: (3.56 – 1) * 100 2.56*100 = +256 For decimal odds lower than 2.00 use the formula -100 / (decimal odds – 1). Example: -100 / (1.20 – 1) -100 / 0.20 = -500 To convert fractional odds to decimal odds use the formula: If the fraction is x/y then (x / y) + 1.00 Example: (5 / 1) + 1.00 5 + 1.00 = 6.00 Or a more complicated example: (7 / 3) + 1.00 2.33 + 1.00 = 3.33 To convert fractional odds to American odds you need to determine what formula to use based on the fraction value if the fraction is equal to x/y. For fractions greater 1, use the formula (x / y) * 100. Example: 5/1 Fractional odds (5 / 1)* 100 5 * 100 = +500 For fractions lower than 1 use the formula -100 / (x / y) Example: 3/7 Fractional odds -100 / (3 / 7) -100 / 0.4286 = -233 To convert American odds to decimal odds, you need to choose the formula based on whether the American odd is an underdog (positive number) or a favourite (negative number). To convert underdog odds to decimal odds use the formula (+x /100) + 1 +400 American odds (400/100) + 1 4+1 = 5.00 To convert favourite odds to decimal odds 100 divided by the positive moneyline amount and add 1.
-400 American Odds (100 /400) + 1 0.25 + 1 = 1.25 To convert American odds to decimal odds, you need to choose the formula based on whether the American odd is an underdog (positive number) or a favourite (negative number). To convert underdog odds to fractional odds, use the formula x / 100 then simplify the fraction if possible. A more complicated example +350 American odds 350 / 100 3.5 = 7 / 2 To convert favourites odds to fractional odds, use the formula -100 / x -100 / -400 0.25/1 * 1000/1000 = 250/1000 The greatest common denominator is 250. A more complicated example: -650 American odds -100 / -650 0.15/1 * 1000/1000 = 150/1000 The greatest common denominator is 50 (150/50)/(1000/50) 3/20 Ready to put your new knowledge into practice? Check out William Hill’s latest sports betting odds. Spent thousands of hours researching every major UK betting app Compared each app across 150+ data points, from usability and speed to features and customer support Created in-depth comparison guides by sport and betting style Gathered
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Here are some examples of US bets, how they would work and how much the bookies will pay out for a win. +250: Bet £100, win £250, profit £350 +250: Bet £10, win £25, profit £35 -125: Bet £125, win £25, profit -£100 -125: Bet £10, win £2, profit -£8 To convert US odds to percentages, use these rules: The odds themselves are the profit therefore the percentage of return is the odds + 100% of the wager. You can use this to work out how much money will be returned if you win. With odds of +250 this equals 250%. If you wager £100, with a successful bet you would profit £250 including the betted £100 equaling 350%.
To convert favourites odds to a percentage, use the formula 100 – (10000 / +odds) the bettor bets £100 with -125 odds. This equals 20% of what you wagered. Therefore £100 * 20% equals a £20 return or an £80 loss. To calculate the probability from an underdog American odds, use the same method as fractional odds. Using the example +250 odds with a £100 bet.
Divide the odds by 100 and use the formula (y / (x + y)) * 100 where odds are x/y. (1 / (2.5 + 1)) * 100 (1 / 3.5) * 100 0.2857 * 100 28.57% win probability To calculate the probability from a favourites American odds, use the same formula as above but subtract the final number from 100. 100 – ((1 / (2.5 + 1)) * 100) 100 – ((1 / 3.5) * 100) 100 – (0.2857 * 100) 100 – 28.57 71.43% win probability. The William Hill website automatically does this for you. On desktop you can see the option to change the odds format in the top right. BetVictor is regarded as one of the UK’s most complete betting apps, known for consistently strong football and horse racing odds and a wide selection of ongoing promotions for mobile users.
| Region/Country | Status of Odds Comparison | Licensing Required? | Major Restriction |
|---|---|---|---|
| United Kingdom | Fully legal & regulated | Yes (Affiliate License) | Must promote licensed operators only |
| United States (New Jersey) | Legal in regulated states | Varies by state | Must geo-block unregulated states |
| Germany | Legal | No direct license needed | Strict advertising content rules |
| Australia | Legal with restrictions | No | Cannot promote "in-play" betting features |
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