Kelly Criterion Calculator: Optimize Bets for Free

Last Updated on 02/22/2026
Fact checked by: Meghan

Our Kelly Criterion calculator is a handy tool that helps you to implement one of the most effective long-term betting strategies. By inputting your total bankroll, odds and probability, you can find out the ideal stake for your bet.

If you want to take a more conservative approach to the Kelly Criterion, you can use the fractional tool to cut your bet between 0.10 and 0.90 of the total recommended stake. What’s important to note is that if the calculator returns a negative stake, the bet is not worthwhile at the given odds.

Use our free Kelly Criterion Calculator to your advantage

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How to use the Kelly Criterion betting calculator

To use the Kelly Criterion calculator, you need to enter either your total bankroll, or your sportsbook account balance first. Next, you’ll need to enter the odds for your chosen bet and the probability of winning.

You can also use the fractional tool, should you wish to be a bit more conservative. By default our calculator will give you the ‘full’ amount that you should wager, shown as ‘1’, but you are at liberty to adjust by increments to between 0.10 and 0.90.

Here’s a close look at all of the information that you need to enter:

Betting account balance/bankroll

This is either the total amount of money you have available in your sportsbook account, or across all of your sports betting app accounts. Basically, it’s the budget that you have available for sports betting - which should be no more than you can realistically afford to lose, of course.

Odds

Plain and simple, you need to enter the odds for your chosen single-stake bet.

Win probability

Finally, you need to enter your win probability as a percentage. You can simply convert the odds to get this. Additionally, if you want to get a more accurate win probability, we recommend using our no-vig fair odds calculator.

Fractional Kelly Criterion betting tool (Optional)

As standard this will be set to 1, however, you can use this tool to reduce the value to anything between 0.10 - 0.90 if you wish to take a more conservative approach to this betting strategy.

A step-by-step guide to using the Kelly formula calculator:

Now that you have a full understanding of the values that you need to input into the calculator here’s a walkthrough guide for the full process of using this tool:

  1. Find the odds for the event/player that you want to bet on
  2. Open your Kelly Criterion calculator
  3. Insert all of the required values as described above (bankroll, odds and win probability)
  4. Use the fractional tool for more conservative results (optional)
  5. Once you are happy, click the “Calculate” button to get your results

If the calculator gives you a negative (-) value, it means that you should not place the bet at those odds. However, if the value is positive (+), it will return two figures:

  • Recommended stake - The amount of money that you should ideally wager based on the information provided.
  • Expected Value (EV) - The expected profit/value of the bet based on the EV formula. Basically, it shows the average profit you could make from the bet, at the given odds, if you were to place it multiple times.

Example - The Kelly calculator in action

Enough of the theory, let’s take a look at how the Kelly Criterion calculator works in action by using a real-life example. Let’s say you fancied Utah Jazz to beat the Chicago Bulls as slight underdogs at +164 on the moneyline.

If you were to convert the odds, you would get an implied probability figure of 37.88%. However, if you put this value into the calculator, you will always get a $0.00 result.

This is because sportsbooks distort the odds slightly to add the “vig”, which is effectively their commission. You therefore need to try and find the real probability, which you can do using our no-vig fair odds calculator.

Once you know your total bankroll, odds and win probability, here’s how it would look if you had a total bankroll of $1,000 and calculated using a 40% win probability:

Total bankroll:$1,000
Sportsbook odds:+164
Win probability (not from sportsbook):40%
Fractional betting:1.0

Using our calculator with those inputs returns the following output:

  • Recommended bet: $34.15
  • Percentage of bankroll: 3.41%
  • Expected Value (EV): $1.91
  • Total returns: 5.6% of funds wagered

The Kelly Criterion explained

So we’ve covered how to use the Kelly Criterion calculator in great detail, now let’s look at the theory, strategy, and formula behind it. The Kelly Criterion, or Kelly bet formula, is a method you can use to determine your ideal bet size, based on the odds, winning probability and your total bankroll.

An effective long-term betting strategy

The Kelly Criterion is a long-term betting strategy that is designed to help you maintain your bankroll and perhaps even grow it steadily over time. As a result, you will rarely find large EV and return percentages when using the calculator.

At the same time, if a bet is too short, with no value or a low win probability, the calculator will return a negative stake. In such cases, you should avoid these bets if you intend to stick to the strategy.

Name and origin

Randomly, the Kelly Criterion was originally a formula invented by lab researcher, John Kelly, as a means of analyzing the noise on long-distance telephone signals. However, it has since been adapted and is now most commonly implemented as a long-term strategy by sports bettors.

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Why the Kelly betting calculator is useful

If you want to maintain and build your bankroll over time, the Kelly Criterion calculator is probably the most useful of all our sports betting tools here at PromoGuy US. Just remember that it is not a quick fix and you have to be patient.

Below is a summary of the top five uses of this calculator and betting strategy:

Manage your bankroll

Before we get to the potential wins and profits, this calculator, first and foremost, can help to maintain your bankroll. Before you can think about winning money, it’s important to make sure you don’t lose any.

Find your ideal bet size

The EV and returns percentages are useful, but the most important figure is your ideal bet size. This is what can help you to implement the Kelly betting strategy most effectively.

Know which bets to avoid

As explained, if you get a minus or $0.00 result, you know that that particular bet at those odds should be avoided. This is another way it can help to eliminate losses and stop you from making poor or impulsive betting decisions.

Flexibility

The fractional tool within our Kelly bet calculator allows you to move the dial to make your calculation standard or more conservative. This provides an extra level of flexibility that many other Kelly calculators don’t offer.

Maximize potential profits

Although you won’t land big wins (relative to your bankroll) you can still maximize your potential profits over time. As well as the profits from your winning bets, you also have the advantage of a calculator helping to minimize your risk exposure and losses.

What other betting calculators are available?

We have over 15 betting calculators available for you to use here at PromoGuy US, which can help with everything from basic odds conversion to calculating complex strategies and formulas. You can check all of them out below:

All of our free betting calculators at the PromoGuy

Kelly Criterion bet calculator - Conclusion

Even if you’re not a conservative bettor, the Kelly Criterion is a useful calculator if you want to manage your bankroll effectively. It can help you to identify potentially valuable and profitable bets, whilst also identifying those bets you should avoid completely.

At the end of the day, this tool is all about helping you to make the most of your bankroll, regardless of how big or small your betting budget may be. Just remember to set realistic expectations of small payouts that can increase your profits over time.

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Kelly Criterion calculator FAQ

🧐 How is the Kelly Criterion calculated?

The Kelly Criterion is calculated using your total bankroll, the sportsbook odds, and your projected win probability. This will give you the amount of your bankroll that you should use to place the bet. However, if the expected value is negative, you should avoid the bet at those odds altogether.

❓ What is the Kelly Criterion for dummies?

Basically, this is a betting strategy that involves managing your bankroll effectively to achieve profit over time. If you are new to this and want to make it as easy as possible, just enter your bankroll, the odds for the bet, and ther winning probability into our Kelly Criterion calculator here at PromoGuy.us.

🔎 How does the Kelly Criterion work with betting?

In essence, the Kelly strategy works by calculating the amount you should bet based on your total bankroll and the odds offered by the best NBA sportsbooks. For more information, check out our guide and use our calculator here at PromoGuy.us.

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