Free Kelly Betting Calculator for Sports Bettors
A lot of bettors pick a stake amount without putting too much thought or structure behind it. Like making flat bets, gut feeling calls, or doubling up after they lose. And that’s not a great way to bet!
There’s a fix to that, and the Kelly Criterion. It uses a formula to calculate the best stake size based on your odds, your advantage, and, of course, your bankroll.
Our handy calculator gives you a calculated recommendation; how much to bet in order to increase your bankroll over time without taking on any unnecessary risks.
It’s built for bettors who don’t want to just guess anymore. All you do is enter your odds, your estimated win probability, and your total bankroll. Our tool will do the rest! Plus, it’ll give you some safer alternatives depending on how aggressive you want to be.
Kelly Criterion Calculator
What Is the Kelly Criterion?
The Kelly Criterion is a basic formula that calculates how much of your bankroll to risk on a bet, and it’s based on how likely you are to win and how much the bet will pay out.
Instead of betting the same amount every time, it adjusts your stake according to how much value you’ve found. The bigger your edge? The bigger your bet. And the smaller your edge? The smaller your bet. You get the idea!
Here’s the formula it used to calculate:
f = (bp – q) / b
Where:
b = decimal odds minus 1
p = your estimated win probability
q = 1 – p
The result is a percentage of your bankroll to stake. It protects you from overextending on the lower-value bets or under-betting on the strongest ones!
How to Use the Calculator
The tool is super easy to use and shows you results in seconds! All you have to do is follow the steps below:
- Choose your odds format: You can pick American, Decimal, or Fractional.
- Input the odds: Input the betting line for your pick.
- Add your win probability: This is based on your estimate or model.
- Enter your bankroll: Plug in the total amount you’re working with, not just for a single bet.
- Click Calculate: The calculator will show recommended stake sizes and tell you if the bet qualifies as +EV (positive expected value).
And here’s what you’ll see and what the results mean:
- Kelly %: The percentage of your bankroll to risk based on the formula
- Recommended Bet (Full Kelly): The calculated stake if you’re using the full amount
- ½ Kelly and ¼ Kelly: Scaled-down versions for lower variance
- +EV Bet status: This shows if the bet is considered profitable
- Bar graph: A visual breakdown of Full, Half, and Quarter Kelly percentages
Example Calculation
Ok, let’s use a real example using +150 odds, 55% win probability, and a $1,000 bankroll to show you how it works!
- Odds: +150
- Win Probability: 55%
- Bankroll: $1,000
Based on that, the calculator shows:
- Kelly %: 25.00%
- Recommended Bet (Full Kelly): $250.00
- ½ Kelly: $125.00
- ¼ Kelly: $62.50
- +EV Bet: Yes
The bar graph visually shows how each Kelly level compares as a portion of your bankroll. If you’re the cautious type, you can choose the ½ or ¼ Kelly numbers without needing to guesstimate how much to scale down.
When to Use Full Kelly vs. Fractional Kelly
Full Kelly is the most aggressive strategy, as its goal is to get you the fastest bankroll growth, but that means it comes with more risk, chiefly if your win probability estimate isn’t accurate.
½ Kelly and ¼ Kelly decrease the above volatility. The scaled-down versions still work with the formula, but they give you some wiggle room during any downswings.
Here’s when you should go Full Kelly:
- You trust your probability estimate
- You’re betting in volume over time
- You’re okay with bigger swings
And use the Fractional Kelly when:
- You want to decrease volatility
- You’re testing out a new model
- You’re gradually building up your bankroll
What Is a +EV Bet?
What’s a +EV bet? It’s when the odds are in your favor based on your estimated win probability.
If you believe a team has a 55% chance to win and the odds suggest that it’s closer to 40%, that’s a +EV situation. These are the bets that move your bankroll in the right direction in the long run.
The calculator automatically tells you if the math supports the bet. If not? It’ll show that there’s no real advantage in the odds that you entered.
Why This Tool Matters for Serious Bettors
Too often, bettors overlook stake sizing, but it’s one of the biggest factors in long-term profitability. The Kelly Criterion helps you steer clear of staking too small on high-value plays or overcommitting on low-edge spots.
The calculator gives you structure. You won’t be tempted to overreact or make impulsive bets, as you are dealing with a calculated number that lines up with your probability and risk preference/tolerance.
When you use it consistently, it supports managing volatility, staying away from emotional swings, and you’ll get more out of the bets that really matter!
Other Useful Tools
Don’t just stop at using the Kelly Criterion Calculator! We have more tools to get your betting game up, so pair it with the resources below:
- Odds Converter: Switch formats across books instantly
- Arbitrage Calculator: See how to guarantee profits by placing bets on all outcomes.
- Parlay Calculator: Break down payouts across multi-leg bets
- Bet Tracker Tool: Log, review, and improve your betting history
- Smart Bankroll Manager: Organize your roll and plan your future bets
FAQs
The Kelly Criterion isn’t hard to use, but since the formula looks intimidating (fractions, y’all), we compiled a list of the most frequently asked questions our readers have sent us.
What Is the Kelly Criterion?
It’s a formula that calculates how much of your bankroll to stake based on the odds and your estimated advantage.
Do I Have to Use Full Kelly?
Nope! Half and Quarter Kelly are usually better if you want to decrease fluctuations or are working with smaller margins.
What if My Win Probability Is Wrong?
The formula all depends on good input. If your estimate is off, the bet size won’t be right either!
Is This Strategy Legal?
Of course it is! It’s a bankroll management formula that’s used in sports betting, poker, and financial markets. We would never recommend something shady to our readers.
Do Professional Bettors Use This?
They do! Most pro bettors use some form of Kelly staking, usually fractional, so that they can manage repeated and long-term growth.
Use the Kelly Edge to Grow Your Bankroll
This calculator isn’t an excuse to bet bigger; it’s how you bet the right way. If you’ve got an advantage, Kelly enables you to apply it, and you won’t blow through your bankroll
The Kelly Criterion gives you a structured, risk-aware way to size your bets based on real probability and odds instead of with personal bias or out of habit.
You can use the calculator any time you want to check your stake! You can use it to test different lines, look at different scenarios, and track how your advantage translates into action.
If you’re thinking about the long haul, our tool definitely deserves a spot in your regular rotation!