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Adam Haynes
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American odds work against a base value of $100. Odds for favourites (-100) denote the stake required to win $100 while odds for underdogs (+100) display the profit that can be made on a bet of $100.

And there you have it – a very basic answer to the question, “How do American odds work?” If you would like a more detailed explanation with some practical help, keep reading. We cover American odds at online betting sites, how to convert them to other odds formats, and plenty more!

What are American Odds?

American odds – also known as US or Vegas odds – are the main sports betting format used in North American bookmaking. But they can also be used at UK betting sites that allow you to change odds formats. What stands American odds apart from fractional and decimal odds are the positive (+) and negative (-) symbols that precede a bookie’s prices.

Odds with negative signs indicate the stake required to make a profit of $100. Those with positive signs show the potential profit that can be made from a $100 wager. This doesn’t mean you must place a $100 bet each time – this is simply an incremental value used to discern between fighters, runners, or teams in markets. Here is an example of American odds for the winner of the MLB World Series. in baseball.

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We believe there are benefits to using American betting odds. For example, they are generally consistent and easy to understand. Especially when betting on US sports like basketball or baseball. Other odds formats make it tougher to gauge the implied probability of a selection, which can sometimes make it favourable to use American odds.

In much the same way as fractional and decimal formats, understanding American odds can help you identify betting value on football or other sports. It may also come in handy if you are planning a trip to North America or a specific country that uses them.

Example of How American Odds Work

American odds might look strange at first glance. They can certainly spark curiosity if you have never had to use them before. We believe examples are good for answering questions like, how do American betting odds work? So, let’s introduce an easy one.

Here is an example of a moneyline bet placed on Arsenal vs Tottenham in the Premier League.

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As you can see, Arsenal are the favourites and are priced at -138 (8/11) to win. This means a $138 stake is required to make a profit of $100. If you bet $138 and Arsenal beat Spurs, your total returns will be $238 ($138 + $100 = $238).

Spurs are the underdogs at +300 (3/1) and bookies pay out $300 for every winning $100 stake placed on them. If you back Spurs with a $100 stake, total returns will be $400 ($300 + $100 = $400).

Perhaps you fancy the draw at +320 (16/5)? If you make a successful $100 bet on Arsenal and Spurs drawing, your total returns will be $420 ($320 + $100 = $420).

American odds can make it easier to work out potential payout on bets. Especially where favourites, or “plus money” selections, are concerned. You might be wondering, how do American odds work when converted to other formats? Let’s move on to the next section where you explain everything.

American Odds Converter Guide

There may be times when you are looking to work out potential profit or implied probability. Regardless of the bet types or odds formats, everything comes down to maths. Sometimes, you’ll need to figure out American odds that aren’t as simple as +100 (Evens).

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The following sections explain how to convert American sports odds to decimal and fractional formats. And vice versa!

Converting American to Decimal Odds

To convert American to decimal odds, you need both values. The formula is straightforward but must be adjusted depending on whether the sports odds are positive or negative.

Let’s use the example of Manchester United with American odds of +200.

  • Positive Odds Formula – (American Odds / 100) + 1. So, decimal odds for Manchester United are (200/100 = 2) +1 = 3 (3.00).

For the decimal odds, we’ll use the horse Arkle at odds of -400. Notice how the 100 is now flipped in front of the value of the American odds.

  • Negative Odds Formula – (100 /American Odds) + 1. Convert Arkle’s -400 odds to decimal by dividing the value of US odds (400 without the minus symbol) and adding 1 (100/400 = 0.5) + 1 = 1.25 (1.25).

Converting a Decimal to American Odds

There are two ways to work out decimal to American odds. One can be used with odds of 2.00 or more, with the other applied when you use (negative) values of 1.01 to 1.99.

Here is the formula for converting Manchester United’s decimal odds (3.00) back to American odds.

  • Formula for Odds of 2.00 or More – (Decimal Odds – 1) x 100. So, American odds for Manchester United are (3.00 -1) = 2 x 100 = 2.00 (+200).

Converting odds under 2.00 in decimal form to American – such as in Arkle’s (1.25) case – can be slightly more complicated. By understanding betting odds conversions, we can use an easy formula on odds between 1.01 and 1.99.

  • Formula for Odds Under 2.00 – (1/ (Decimal Odds – 1)) x 100. Arkle’s converted American odds work out as (1/(1.25 -1) = 0.25 x 100 = 4 x 100 = 400 (-400).

How do American odds work out at -400 from 400? The decimal format does not account for the plus and minus symbols, meaning these must be added when there is a positive or negative value. Decimal odds under 2.0 are considered negative, which is why you add the minus symbol.

Converting American to Fractional Odds

Most betting sites in the UK display odds in the fractional format. Odds on display for everything from major sports like horse racing to underdog bets in football are fractional by default – this makes it important to know how to convert American odds to fractional.

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Here are examples of how to convert American to fractional odds for Detroit Pistons (+275) vs. Miami Heat (-114). Remember – you don’t add the negative or plus signs to either formula for favourite or underdog bets.

  • Formula for Positive Odds – (American Odds/100) – The Pistons’ fractional odds work out as (100/275) = 2.75 (11/4). The final value of 11/4 is achieved by converting the percentage (275%) to a simple fraction.
  • Formula for Negative Odds – (100/American Odds)This means the Heat’s fractional odds work out as (100/114) = 0.87 (7/8). Again, you get 7/8 by converting the percentage (87%) to a simple fraction.

Converting a Fraction to American Odds

There is also a formula that makes the conversion of odds from fractions to US-style easy. Just remember that a higher number on the left (e.g. the 11 part of 11/4) indicates a plus money (+) favourite. A lower number on the left (7/8) indicates a minus money (-) underdog.

Here’s an example using Detroit Pistons (11/4) and Miami Heat (7/8).

  • Fraction to American for Positive Odds – (Fractional Odds Numerator / Fractional Odds Denominator) x 100 – This shows the American odds for the Pistons are right (11/4 = 2.75 x 100 = 275 (+275).
  • Fraction to American for Negative Odds – (Fractional Odds Numerator / Fractional Odds Denominator) x 100 – You can use the same formula as with the positive odds to get American odds for the Miami Heat, once you turn the numbers around and add a minus to the final value (8/7 = 1.14 x 100 = 114 (-114).

And that’s it – American betting odds explained through examples. We are hoping you won’t need to ask how do American odds work any more, having gone through the above scenarios. Let’s now move on to the most popular markets for US betting odds.

Most Popular Markets That Use American Betting Odds

Many online betting sites offer the chance to wager with different types of betting odds. Some of the popular betting markets with American odds include moneyline wagers, over/unders, and spread betting.

  • Money Line Money line bets are based on the outcome of an event, such as the New England Patriots to win the Super Bowl. They are among the easiest bets to place online.
  • Over/Under – Also known as “totals,” over/under markets allow you to wager on scenarios such as 1.5 goals or more, or the number of points scored in a match.
  • Spread Betting – In the US, spread betting is similar to “handicap” betting, whereby points/goals head starts are given to a team to even the playing field. In the UK, sports spread betting means something different.

You’ll find plenty of sports betting markets that use American odds. Odds are not restricted to one format, either. Whether your initial wager is in the decimal, fraction, or American format, you will find something right for you to bet on NFL games and more.

Pros & Cons of American Odds Explained

Betting odds formats are a matter of personal preference, with some favouring a particular type. Still, there are some benefits and drawbacks to using American odds – especially when wagering on UK gambling sites.


  • Easy to Discern Between Favourite and Underdog Odds
  • Simple to Calculate Winnings from Initial Stake
  • Great to Use When Following/Betting on Live US Sports


  • Not Available on All UK Betting Sites
  • Can be Difficult to Calculate Return on Favourites
  • Tougher to Identify Betting Value Across Multiple Platforms

American Betting Odds Calculator

A bet calculator for American odds can be a great addition to your bookmarks tab. We have designed a system that lets you set the format, which is great if you are used to using US odds.

Use our free bet calculator to convert American odds to decimals. You can transform your moneyline favourites or underdogs into another format.

What are American Odds Bet Calculator

Looking to avoid the headaches of manual calculations? If so, consider how do American odds work when converted at the click of a button.

Best UK Bookies for American Odds

Many of our recommended online betting sites allow you to change odds to the American format. Even after you have placed your original wager. Some of them also have a great range of American-style markets for US sports and leagues like basketball, baseball, and the NFL.

Our recommended bookie for American odds is Betfred. This provides the means to view and place bets on all sports using US odds. More than this, they also have one of the best selections of American sports markets online.


How to read American odds?

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How do payouts work for American odds?

Why are American odds available on UK betting sites?

Adam Haynes

Adam joined bettingsites.co.uk in August 2023, bringing almost a decade of betting knowledge with him. A former writer for Gamblingsites.com, Adam prides himself on spotting a good bet, and loves to share his tips and picks across a wide range of sports and events. Adam is a huge boxing and MMA fan, and started his career writing about both. He is also passionate about his favourite sports teams, which are Glasgow Celtic, Dublin GAA, and Leinster Rugby. At the casino, you're most likely to see him at the poker or blackjack tables. But what he loves more than anything is writing about sports and the gambling industry. You can find his expert insight and commentary right here.