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Using the example +250 odds with a £100 bet.
| Candidate | BetOnline | Bovada | Implied Probability |
|---|---|---|---|
| Donald Trump | +125 | +120 | 44.4% |
| Kamala Harris | +150 | +140 | 40.0% |
| Robert F. Kennedy Jr. | +1200 | +1100 | 8.3% |
| Gavin Newsom | +2500 | +2200 | 4.0% |
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.
| Game | Online Casino A | Online Casino B | Land-Based Casino | Theoretical RTP |
|---|---|---|---|---|
| Blackjack | 99.50% | 99.60% | 99.30% | 99.5%+ |
| European Roulette | 97.30% | 97.30% | 97.30% | 97.3% |
| Slots (Avg) | 96.00% | 95.80% | 92.00% | 92-98% |
| Video Poker (Jacks or Better) | 99.54% | 99.54% | 99.54% | 99.54% |
On mobile, this is located at the bottom of the menu.
| Bookmaker | Manchester City | Arsenal | Liverpool | Odds Format |
|---|---|---|---|---|
| Bet365 | 2.10 | 4.50 | 5.00 | Decimal |
| William Hill | 2.15 | 4.33 | 5.25 | Decimal |
| Pinnacle | 2.08 | 4.60 | 5.10 | Decimal |
| Betfair Exchange | 2.12 | 4.70 | 5.30 | Decimal |
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.
Key Takeaways
They will be fractional, in decimal or American format, each of which will be explained below. Fractional odds use a fractional format to display possibility of an event happening. This is one of the most straightforward ways of determining how much you will win from a bet and is a quick and simple way to understand the probability of an event happening. Here are some examples of fractional bets, how they would work and how much the bookies will pay out for a win. 3/1 – Bookies pay £3 for every £1 staked 15/2 – Bookies pay £15 for every £2 staked 3/5 – Bookies pay £3 for every £5 staked 1/1 – Bookies pay £1 for every £1 staked The first two bets are called “odds-against” bets: a scenario where the bookie thinks the event is more likely not to happen – the bookie is betting against an event occurring and that it is unlikely.
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The third one is an “odds-on” bet: a scenario where the bookie thinks the event is likely to happen. When both numbers are the same (last example), this is an “evens” bet: a 50/50 bet. In this scenario you would double your stake if placing a winning bet. Before making a bet, a bettor may want to take into account the profit and their wager to work out the percentage return if they win. For example, odds of 3/1 would provide a 300% profit as the payout from the bookie, as well as 100% of the money wagered.
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If the bettor wagered £10 and won, their profit would be £30 + the bet bet new customer offers betting uk of £10 = a return of £40. 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. 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.
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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.
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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.
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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. 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. For decimal odds 2.00 or greater use the formula (decimal odds – 1) * 100.
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Example: (3.56 – 1) * 100 2.56*100 = +256 For decimal odds lower than 2.00 use the formula -100 / (decimal odds – 1).
How to calculate Implied Probability from Decimal Odds
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.
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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.
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Indicates bet best new customer offers betting app what you must bet to make £100 profit. 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%. 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.
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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).
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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. 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).
Other Odds Comparison Sites
The odds are calculated by the bookmaker. They will estimate the probability of an event taking place and based on their prediction, will display odds. William Hill offers the reader and bettor the opportunity to request their own odds. Through the popular #YourOdds on Twitter, punters can request odds on an outcome not listed by the bookie at the time and be one of the first to place a bet on a specific outcome of their choice. The social media team will pass on the punter’s requests to the traders upstairs, and if the request is approved, the punter will be able to bet on their own fully customised odds on the day they requested them before anyone else.
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You are looking for odds on something you want to bet on? On William Hill’s website, you will find the odds you are looking for and a breakdown of what the odds are for specifically. William Hill offers odds for many different aspects of an individual event. For example, for a football match, you could bet on goals scored, yellow cards, fouls, corners in the first half or the final score. Each outcome will have been priced up individually based on the probability of it happening.
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You will likely come across fractional odds first when looking for betting odds. Fractional odds, for example, show us our potential winnings if we wager the corresponding stake. The number on the left-hand side is your winnings if you were to stake the figure on the right-hand side. For example, with odds of 10/1, £10 would be your winnings if you placed a £1 bet and won. To read the betting odds, click on the event you are interested in and take note of the odds listed. 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.
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