How to Calculate Betting Odds for Beginners: A Simple Guide

On Aug 25, 2025

Picture this: You’re watching your favorite team play, and you want to place your first bet. You open a sportsbook app and see numbers like “+150,” “2.50,” and “3/2” next to different teams. What do these numbers mean? How do you know if a bet is worth making?

Understanding betting odds for beginners doesn’t have to feel like solving a math puzzle. These numbers are simply the sportsbook’s way of telling you two things: how likely something is to happen and how much money you can win.

Learning how to calculate betting odds for beginners is like learning to read a map before taking a road trip. You wouldn’t drive somewhere new without knowing the directions, and you shouldn’t bet money without understanding what the odds mean. This guide will teach you everything you need to know using simple math and real examples.

What Are Betting Odds?

Betting odds are numbers that show you the probability of something happening in a game or match. Think of them like weather forecasts. When the weather app says there’s a 70% chance of rain, you know it’s probably going to rain. Betting odds work the same way – they tell you how likely a team is to win.

There are three main types of betting odds you’ll see:

American Odds (Most Common in the US)

American odds use plus (+) and minus (-) signs with numbers like +200 or -150.

Positive odds (+200): These show you’re betting on the underdog. The number tells you how much profit you’d make on a $100 bet.
Negative odds (-150): These show you’re betting on the favorite. The number tells you how much you need to bet to win $100.

Decimal Odds (Popular in Europe)

Decimal odds look like regular numbers: 2.50, 1.75, 3.00. These are actually the easiest to understand because they show you exactly how much money you’ll get back for every dollar you bet.

Fractional Odds (Traditional in the UK)

Fractional odds look like fractions: 3/1, 2/5, 7/2. The first number shows your potential profit, and the second number shows how much you need to bet.

How Betting Odds Work

Before diving into calculations, let’s understand what odds really represent. Every set of odds contains something called implied probability – the percentage chance that the sportsbook thinks something will happen.

Think of it like this: If you flip a coin, there’s a 50% chance it lands on heads and a 50% chance it lands on tails. If sportsbooks offered odds on coin flips, they’d reflect these percentages.

In sports, nothing is guaranteed like a coin flip. Teams have different strengths, injuries, and advantages. Sportsbooks use all this information to create odds that reflect each team’s chances of winning.

Here’s the key point: sportsbooks don’t just predict what will happen, they also build in their profit. This is called the “vig” or “juice.” It’s how they make money regardless of who wins.

Step-by-Step Guide: Calculating Odds

Let’s break down how to calculate each type of odds with simple math.

Calculating American Odds

For Positive Odds (+):

Formula: (Odds divided by 100) times Your Bet = Profit
Total Return = Profit + Your Original Bet

For Negative Odds (-):

Formula: (100 divided by Odds) times Your Bet = Profit
Total Return = Profit + Your Original Bet

Calculating Decimal Odds

Formula: Your Bet times Decimal Odds = Total Return Profit: Total Return minus Your Original Bet

This is the simplest calculation. If the odds are 2.50 and you bet $20: $20 times 2.50 = $50 total return $50 minus $20 = $30 profit

Calculating Fractional Odds

Formula: (First Number divided by Second Number) times Your Bet = Profit Total Return: Profit + Your Original Bet

Converting Odds to Implied Probability

American Odds:

For positive odds: 100 divided by (Odds + 100) times 100 = Probability %
For negative odds: (-Odds) divided by (-Odds + 100) times 100 = Probability %

Decimal Odds: 1 divided by Decimal Odds times 100 = Probability %

Fractional Odds: Second Number divided by (First Number + Second Number) times 100 = Probability %

Examples for Beginners

Let’s work through some real examples using small amounts of money.

Example 1: American Odds (+150)

You want to bet $10 on a team with +150 odds.

Calculation:

(150 divided by 100) times $10 = 1.5 times $10 = $15 profit
Total return: $15 + $10 = $25

What this means: If you bet $10 and win, you get back $25 total ($15 profit plus your original $10).

Example 2: American Odds (-200)

You want to bet $20 on a favorite with -200 odds.

Example 3: Decimal Odds (3.00)

You want to bet $15 with decimal odds of 3.00.

Calculation:

$15 times 3.00 = $45 total return
$45 minus $15 = $30 profit

Example 4: Fractional Odds (5/2)

You want to bet $8 with 5/2 odds.

Calculation:

(5 divided by 2) times $8 = 2.5 times $8 = $20 profit
Total return: $20 + $8 = $28

Common Mistakes Beginners Make

Mistake 1: Not Understanding the Difference Between Profit and Total Return

Many beginners think the odds show their total return, but often odds show only profit. Always double-check whether you’re calculating profit or total return.

Mistake 2: Betting Based on Odds Alone

Just because a team has high odds doesn’t mean it’s a good bet. High odds usually mean low probability of winning. Don’t chase big payouts without considering the risk.

Mistake 3: Ignoring Implied Probability

Understanding implied probability helps you spot value bets. If you think a team has a 60% chance of winning but the odds suggest only 40%, that might be a good bet.

Mistake 4: Betting Too Much Too Soon

Start with small amounts while you learn. Even if you understand the math, sports betting involves luck and unpredictable events.

Mistake 5: Not Shopping for Better Odds

Different sportsbooks offer different odds for the same game. A difference of even 10-20 points can affect your profits significantly over time.

Tips for Smarter Betting

Start with a Budget

Decide how much money you can afford to lose before you start betting. This should be “entertainment money” – not money you need for bills or savings.

Use the 1-5% Rule

Never bet more than 1-5% of your total bankroll on a single game. If you have $100 to bet with, don’t put more than $1-5 on any single bet.

Keep Records

Track your bets, wins, and losses. This helps you see patterns and learn from your mistakes. Write down:

Date and game
Amount bet
Odds
Result
Profit or loss

Focus on Sports You Know

You’ll make better betting decisions on sports you understand. If you’ve watched basketball for years, you’ll have better instincts about basketball bets than sports you rarely follow.

Learn About Value Betting

A value bet is when you think the real probability of something happening is higher than what the odds suggest. For example, if you think a team has a 50% chance of winning but the odds suggest only 40%, that’s potential value.

Don’t Chase Losses

If you lose a bet, don’t immediately place a bigger bet to “win it back.” This leads to bigger losses. Stick to your plan and budget.

Take Breaks

Betting should be fun, not stressful. If you’re feeling frustrated or betting more than planned, take a break.

Conclusion

Learning how to calculate betting odds for beginners is the first step toward making informed betting decisions. Remember these key points:

American odds show profit on $100 bets (positive) or amount needed to win $100 (negative)
Decimal odds show your total return for every dollar bet
Fractional odds show profit compared to your bet amount
All odds contain implied probability – the sportsbook’s prediction of what will happen
Start small, keep records, and never bet more than you can afford to lose

Understanding betting odds explained through simple math and examples gives you the foundation to make smarter bets. But remember, even with perfect calculations, sports involve unpredictable events. Injuries, weather, and pure luck all play roles.

Use this simple guide to betting odds as your starting point, but always bet responsibly. Set limits, stick to them, and remember that betting should enhance your enjoyment of sports, not create financial stress.

The most successful sports bettors aren’t the ones who win every bet – they’re the ones who understand the math, manage their money wisely, and make informed decisions based on research and probability rather than emotions or hunches.