IMPLIED PROBABILITY CALCULATOR

1. What is an Implied Probability Calculator?

An implied probability calculator converts betting odds into the percentage probability represented by those odds.

For example, decimal odds of 2.00 imply a probability of 50%, while American odds of -200 imply approximately 66.67%.

Implied probability helps you:

• Understand what sportsbook odds mean as a percentage
• Compare prices across sportsbooks
• Evaluate whether your own probability estimate differs from the market price
• Convert American, decimal and fractional odds quickly

Implied probability is not necessarily the true chance of an outcome, because sportsbook odds usually include vig.

2. How to Use an Implied Probability Calculator

Using an implied probability is simple. It involves two steps:

1. Input the Odds You Wish to Convert: If they include a + or - (such as +110) they're American odds. If they're displayed as a decimal (such as 2.1) they're decimal odds. If they're displayed as a fraction (such as 11/10) they're fractional odds.
   
   
2. View your Probability Percentage: Our calculator will instantly convert your odds into a percentage. This percentage is the probability that your selection will win (implied by the odds).

Bonus Feature: As well as being able to convert all three main odds types into a percentage, our calculator automatically converts your odds into the equivalent across the other two types, should you want to compare.

💬
What Our Experts Say

"One of the most underrated uses of an implied probability calculator is identifying when the odds may not align with your own research. If you consistently spot mismatches, you're already thinking like a value bettor, even without realizing it!"

- Chris Allen, Sports & Matched Betting Expert at ProfitDuel

3. Worked Example: Using an Implied Probability Calculator Sports Betting

Let's use an example of how this might work using two teams in the NFL. The Detroit Lions are playing the New England Patriots.

You log in to an online sportsbook to check the odds, and see the moneyline odds for the Detroit Lions to win are -300 and the odds for the New England Patriots to win are +190.

The Patriots' +190 odds imply a probability of 34.48%. If your own research suggests their true chance of winning is higher than 34.48%, the price may be worth investigating further.

However, implied probability alone does not prove that a bet offers value. You should also consider the sportsbook's vig and the reliability of your own probability estimate.

4. How an Implied Probability Calculator Works: The 4 Formulas

You don't need to read this section to be able to calculate implied probability...Our handy calculator does that for you! But if you're curious to know the math behind how to calculate implied probabilities, this section is for you.

In a nutshell, there are four different formulas for calculating implied probability, depending on the odds type you enter.

i) American Odds Underdog (+ symbol)

If American odds start with a plus symbol, this signifies they are positive odds and are the underdogs in the match.

The formula for calculating the implied probability of positive odds = 100/(Positive Odds + 100) x 100.

ii) American Odds: Negative Odds

For negative American odds:

Implied Probability = |American Odds| ÷ (|American Odds| + 100) × 100

For example, at -300:

300 ÷ (300 + 100) × 100 = 75%

iii) Decimal odds

Also known as European odds, decimal odds are often seen as the easiest to understand on first glance. As such, their implied probability is also pretty easy to calculate.

The formula for calculating the implied probability of decimal odds = (1/Decimal Odds) x 100.

iv) Fractional odds

Often referred to as British odds, fractional odds show the ratio of your stake you will win if your bet wins. I.e. if you bet $1 on 11/1 odds and it wins, you win $11.

The formula for calculating the implied probability of fractional odds = Denominator/(Numerator + Denominator) x 100.

Odds Types and Their Implied Probability Formulas

5. Why Is Implied Probability Useful?

Converting odds into implied probability makes sportsbook prices easier to understand.

It can help you:

• Compare the same outcome across sportsbooks
• Understand how strong a favorite or underdog is according to the odds
• Compare sportsbook prices with your own probability estimate
• Use related calculations such as expected value and no-vig probability

Implied probability does not predict the result of an event. It simply translates odds into a percentage.

Key Benefits

💬
What Our Experts Say

"Odds alone don’t always reveal the full story but when converted to implied probability, they can unlock patterns, reveal value, and expose sportsbook biases that casual bettors often miss. It’s a simple tool that builds sharper intuition over time."

- Casey Halpern, Sports Betting Expert at ProfitDuel

6. Limitations of Implied Probability

Implied probability is useful, but it has some important limitations:

• Sportsbook odds include vig, so implied probabilities across a complete market can total more than 100%.
• Odds can move, meaning the implied probability can change quickly.
• It is not a prediction of what will actually happen.
• Value requires comparison with a fair or independently estimated probability.

If you want to remove the sportsbook margin, use our No-Vig Calculator.

7. Implied Probability vs No-Vig Probability

Implied probability is the probability represented directly by sportsbook odds.

No-vig probability adjusts those probabilities by removing the sportsbook's built-in margin.

For example, two sides priced at -110 each have an implied probability of approximately 52.38%. Together, that equals 104.76% because the sportsbook margin is included.

After removing the vig, the fair-market probability would be approximately 50% for each side.

Use the Implied Probability Calculator when you want to convert individual odds into a percentage. Use the No-Vig Calculator when you want to estimate fair-market probabilities across a complete market.

8. Don't Leave it to Chance: How to Lock in a Betting Profit Every Time

Though in traditional sports betting there's no such thing as a ‘dead cert’, there is one approach in the betting scene that's recently gained major traction for its ability to return a profit no matter the outcome.

Matched betting has been available in the US for the last five years, and every year, more and more states are opening their doors to it.

A clever process, matched betting (in a nutshell) involves placing bets to cover every outcome of a game to unlock a sportsbook promo, like a free bet, without the risks of traditional gambling. Once this has been unlocked, you repeat the process on another event using your promo to lock in a profitable payout, turning your bonus into cash.

Though on paper this process may sound simple, to make any significant profit from it you need powerful odds-matching software, a constantly updating dashboard of promos and personalized instructions to rapidly complete each offer… and that's where we come in.

At ProfitDuel we've helped more than 500,000 of our members make profits from matched betting here in the US and in Europe (through our European arm, OddsMonkey) using industry-leading software strategies and support.

The best part? We're offering a ProfitDuel trial to new members when you sign up today! This gives you access to all ProfitDuel software, strategies and support. 

Go ahead, see what you're missing, you'll never need to work out implied probability again!

FAQs on the Implied Probability Calculator

What is implied probability in betting?
Implied probability is the percentage chance represented by a set of sportsbook odds.

How do you convert odds to probability?
The formula depends on whether the odds are American, decimal or fractional. ProfitDuel's calculator converts all three automatically.

What probability does +200 imply?
American odds of +200 imply a probability of approximately 33.33%.

What probability does -200 imply?
American odds of -200 imply a probability of approximately 66.67%.

Does implied probability include vig?
Yes. Sportsbook odds normally include a margin, so the combined implied probabilities of every outcome can exceed 100%.

Is implied probability the same as true probability?
No. Implied probability is based on sportsbook odds. The actual probability of an outcome is unknown and may differ from the price being offered.

What is the difference between implied probability and no-vig probability?
Implied probability comes directly from sportsbook odds. No-vig probability removes the sportsbook margin to estimate a fair-market probability.

What is ProfitDuel?

ProfitDuel’s free betting calculators make it easy to execute strategies like matched betting, arbitrage, and EV betting with precision. By simplifying complex calculations into instant results, our tools help you make fast, confident, profit-driven decisions every time you place a bet.

Trusted by over 500,000 users across the USA and UK, ProfitDuel is the smart betting toolkit built to help you maximize profit and minimize risk. We equip our members with real-time data, cutting-edge tools and expert support to help our members make profits through strategy, not luck.

Centered around proven techniques like matched betting, arbitrage betting, and value betting (EV betting), our betting calculators, betting tools and live market data make it easy to spot hidden edges and turn them into profit. From converting sportsbook promos and casino bonuses into cash to maximizing your long-term winnings with EV software, we’ve got you covered.

Whether you’re an experienced bettor sharpening your edge or a beginner looking for a profitable side hustle, ProfitDuel gives you the software, systems and expert support to boost your monthly earnings with confidence. Because the smartest way to bet isn’t gambling — it’s strategy.