Kelly Criterion Python Helper Function

A simple and efficient Python function that calculates the optimal bet size using the Kelly Criterion formula.
This helps bettors or investors determine the ideal percentage of their bankroll to stake on an opportunity based on the odds and probability of success.

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🧮 Formula Overview

The Kelly Criterion is a mathematical formula used to determine the optimal fraction of your bankroll to wager:

[ f^* = \frac{bp - q}{b} ]

Where:

• f* = fraction of your bankroll to bet
• b = decimal odds - 1
• p = probability of winning
• q = probability of losing = 1 - p

In this script, the final bet amount is scaled by the user’s available bankroll (amt).

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⚙️ Function Definition

def cal(odd, pba, amt):
    odd = float(odd)
    pba = float(pba)
    odd -= 1  # Convert to profit-based odds

    proba = round(pba / 100, 4)
    loss = 1 - proba

    if odd == 0:
        return 0

    f = round((((odd * proba) - (loss)) / odd) * amt)
    return f
🧩 Parameters
Parameter	Type	Description
odd	float	Decimal odds of the bet (e.g. 2.5)
pba	float	Win probability (in percentage, e.g. 55 for 55%)
amt	float	Total bankroll amount
💻 Example Usage
from kelly import cal

odd = 2.0        # Betting odds
pba = 55         # 55% probability of winning
amt = 1000       # Total bankroll in naira

bet_size = cal(odd, pba, amt)
print("Recommended Bet:", bet_size)

🧾 Output
Recommended Bet: 100


(This means you should bet ₦100 from a ₦1000 bankroll.)

💡 Example Use Case

This function can be integrated into:

Automated football betting bots

Investment position sizing tools

Risk management systems

Portfolio optimization algorithms

🧰 Tech Stack

Python 3

Built-in math (no external libraries required)

👨‍💻 Author

Ezee Kits
Focused on Python automation, data analysis, and intelligent betting systems.
📺 YouTube: Ezee Kits

📄 License

This project is licensed under the MIT License — you are free to use, modify, and share with proper credit.