The Easy Way to Calculate American Odds


Paul Harrison
Written By Paul Harrison

The Easy Way to Calculate American Odds


American odds might look a bit intimidating at first, but once you get the basics down, it’s a walk in the park.

If you’re betting on American sites, you’ll need this, as many of them don’t have a way to convert from American to decimal odds. Some of the bigger sites offer odds conversions though, so there you won’t have to worry about manually calculating the odds.

Without further ado, let’s break it down and you’ll get the idea in just minutes.

What Are American Odds?

American odds are either positive (+) or negative (-) numbers.

  • Positive Odds (like +150) show how much profit you make on a $100 bet.
  • Negative Odds (like -150) show how much you need to bet to win $100.

Here’s the main thing to remember: Positive odds indicate the underdog, while negative odds represent the favourite.

Let’s make this super clear with some quick examples:

  • Positive Odds: Say the odds are +200. If you bet $100, you’ll win $200 in profit. So, your total payout is $300 ($100 original bet + $200 winnings).
  • Negative Odds: Now, if the odds are -200, you’ll need to bet $200 to win $100. So, if your bet wins, you’ll get $300 in total ($200 original bet + $100 winnings).

A Quick Example

Let’s say you’re betting on a football game:

Team A has odds of +150:
You bet $100, and if Team A wins, you make $150 in profit. So, you walk away with $250 ($100 bet + $150 winnings).
Team B has odds of -120:
You bet $120, and if Team B wins, you make $100 in profit. In total, you get $220 back ($120 bet + $100 winnings).

Not that intimidating, right?

How to Convert American Odds to Decimal Odds

You’re probably already familiar with decimal odds, as that’s what we use here in the UK. Here’s how you can convert them into American odds.

For positive American odds, here’s the formula:

Decimal Odds = (American Odds / 100) + 1

For negative American odds, the formula changes slightly:

Decimal Odds = (100 / American Odds) + 1

Conversion Example

Let’s try converting American odds to decimal:

  • +150:
    Decimal odds = (150 / 100) + 1 = 2.50
  • -120:
    Decimal odds = (100 / 120) + 1 = 1.83

Common Odds Table

Here’s a table that shows some common American odds and their decimal equivalents:

Calculating American Odds Explainer

Personal Tips for Betting Smarter

Look for value

It’s tempting to always bet on the favorite, but sometimes, the underdog offers better value. I like to scan for odds where the potential reward is high for a reasonable risk.

Shop around for odds

Different sportsbooks can have slightly different odds for the same event. Trust me, getting better odds—even if it's just a little bit—adds up over time.

Know the implied probability

Every set of odds reflects the chance (or probability) of an event happening. Higher negative odds mean a higher chance of winning, while higher positive odds mean a lower chance.

Here’s how you can calculate the implied probability:

For positive odds:
Implied Probability = (100 / (American Odds + 100)) multiplied by 100

For negative odds:
Implied Probability = (American Odds) divided by (American Odds + 100), multiplied by 100

Do Any Casinos Give Better Odds Than Others?

Absolutely! Not all casinos or sportsbooks offer the same odds. Sometimes, smaller or newer online casinos might give better odds to attract new players. We always recommend checking out a few different places before placing your bets.

A good place to start is by checking out the best online casinos listed at CasinoWhizz. They do a great job of reviewing and ranking online casinos, so you’ll have a better idea of where to find good odds.

Wrapping It Up

Once you understand the basics of American odds, they’re not so tricky. Just takes a little practice at first. After a while you’ll be able to just glance at the odds like you do with decimal odds, and get the idea right away.

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