American Odds Explained: How They Compare to Decimal & Fractional Odds

Learn the difference between U.S., European, and UK odds formats with simple examples and calculations.

Table of Contents

1. What Are American Odds?

2. How to Read and Interpret American Odds

3. How to Convert American Odds to Probability

4. American vs Decimal Odds

5. American vs Fractional Odds

6. Real-World Examples

7. Summary / Takeaways

Introduction

There are three major ways to display betting odds: American, decimal, and fractional. Understanding these formats isn’t just trivia—it affects how you calculate risk, payout, and betting value. If you're betting in the U.S., you'll mostly see American odds. But if you're reading European websites or watching UK sportsbooks, expect decimal or fractional. Let’s break it all down.

What Are American Odds?

American odds (also called “moneyline odds”) are based around winning or risking $100. They come in two types:

• Positive odds (+) show how much profit you'd make on a $100 bet.

• Negative odds (–) show how much you'd need to bet to win $100.

  
  

Example:

• +200 = You bet $100, win $200 profit

• -150 = You bet $150 to win $100 profit

  
  
  
  

How to Read and Interpret American Odds

Here’s how to spot the difference between a favorite and an underdog:

Odds	Type	Meaning
-200	Favorite	You need to bet $200 to win $100
+150	Underdog	You win $150 from a $100 bet

Why It Matters:

• Favorites are more likely to win, but pay less.

• Underdogs are riskier, but reward more.

  
  

How to Convert American Odds to Probability

To understand value, convert odds into implied probability. Here's how:

For positive odds (+X):

Probability % = 100 / (odds + 100) × 100

Example: +200= 100 / (200 + 100) × 100 = 33.3%

For negative odds (–X):

Probability % = odds / (odds + 100) × 100

Example: -150= 150 / (150 + 100) × 100 = 60%

American vs Decimal Odds

Bet Type	American	Decimal	Profit on $100 Bet
Favorite	-150	1.67	$66.67
Even	+100	2.00	$100
Underdog	+200	3.00	$200

Decimal Formula:Decimal = (American odds / 100) + 1 (for positive)Decimal = 100 / abs(American) + 1 (for negative)

American vs Fractional Odds

Bet Type	American	Fractional	Meaning
Favorite	-150	2/3	Bet $3 to win $2
Even	+100	1/1 (Evens)	Bet $1 to win $1
Underdog	+200	2/1	Bet $1 to win $2

Fractional odds are common in the UK. They're written like "5/1" or "1/2" and show profit relative to your stake.

Real-World Examples

Example 1: NFL Game

• Patriots -200 vs Jets +170

  • Patriots = Favorite → You must bet $200 to win $100

  • Jets = Underdog → Bet $100 to win $170

    
    

Example 2: UFC Fight

• Fighter A: +135, Fighter B: -165

  • Bet $100 on Fighter A = $135 profit

  • Bet $165 on Fighter B = $100 profit

  
  

Summary / Takeaways

• American odds use + and – to show underdogs and favorites.

• +150 means $100 wins you $150.

• -150 means you need $150 to win $100.

• Decimal odds are easier for calculations (common in Europe).

• Fractional odds are popular in the UK and betting shops.

• You can convert odds to implied probability to find value.

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