🐍 Create a Python Program to Generate Fibonacci Series up to N Terms (Step-by-Step Guide)

The Fibonacci series is a sequence where each number is the sum of the two preceding ones, starting from 0 and 1. It looks like this:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...

This pattern is widely used in mathematics, coding interviews, and algorithm development. In this blog, we'll create a Python program to generate the Fibonacci series up to N terms and explain every step clearly, so even beginners can understand it easily.

🔢 What is the Fibonacci Series?

A Fibonacci series follows this rule:

F(n) = F(n-1) + F(n-2)

With:

F(0) = 0
F(1) = 1

So:

F(2) = F(1) + F(0) = 1 + 0 = 1
F(3) = F(2) + F(1) = 1 + 1 = 2
and so on…

🧠 Logic to Generate Fibonacci Series in Python

We will:

Ask the user to enter the number of terms N.
Print the first two terms manually: 0 and 1.
Use a loop to calculate the next terms using the formula: next = first + second.
Update the first and second terms.
Continue this until we reach N terms.

🧑‍💻 Python Code to Generate Fibonacci Series

# Program to generate Fibonacci series up to N terms

# Step 1: Ask the user for number of terms
n_terms = int(input("Enter the number of terms: "))

# Step 2: Check if the number is valid
if n_terms <= 0:
    print("Please enter a positive number.")
elif n_terms == 1:
    print("Fibonacci sequence up to 1 term:")
    print(0)
else:
    print("Fibonacci sequence:")
    first = 0
    second = 1
    print(first, second, end=" ")  # Print first two terms

    # Step 3: Use loop to print next terms
    for _ in range(2, n_terms):
        next_term = first + second
        print(next_term, end=" ")
        first = second
        second = next_term

🔍 Step-by-Step Explanation

✅ Step 1: Take Input from User

n_terms = int(input("Enter the number of terms: "))

This line asks the user how many terms of the Fibonacci series they want. The int() function converts the input string to an integer.

✅ Step 2: Validate the Input

if n_terms <= 0:
    print("Please enter a positive number.")

Here we make sure the user gives a positive number. If not, we ask them to try again.

✅ Step 3: Handle Edge Case (Only 1 Term)

elif n_terms == 1:
    print("Fibonacci sequence up to 1 term:")
    print(0)

If the user enters 1, we just print the first Fibonacci number, which is 0.

✅ Step 4: Print the First Two Numbers

print("Fibonacci sequence:")
first = 0
second = 1
print(first, second, end=" ")

We manually print the first two numbers because every Fibonacci sequence starts with 0 and 1.

✅ Step 5: Use Loop to Print the Remaining Terms

for _ in range(2, n_terms):
    next_term = first + second
    print(next_term, end=" ")
    first = second
    second = next_term

range(2, n_terms) starts from 2 because we've already printed the first two terms.
We calculate the next number by adding the previous two.
Then we shift the numbers: first becomes second, and second becomes next_term.
print(..., end=" ") keeps all numbers on the same line.

🧪 Sample Output

Input:

Enter the number of terms: 7

Output:

Fibonacci sequence:
0 1 1 2 3 5 8

🎯 Why This Program is Important

Helps understand loops, conditions, and variables in Python.
Great for practicing problem-solving.
Commonly asked in coding interviews and college assignments.

💡 Bonus: How to Generate Fibonacci Using a Function

Here’s a reusable function version:

def fibonacci_series(n):
    first = 0
    second = 1
    series = []
    if n <= 0:
        return []
    elif n == 1:
        return [0]
    series.extend([0, 1])
    for _ in range(2, n):
        next_term = first + second
        series.append(next_term)
        first = second
        second = next_term
    return series

# Example usage
n = int(input("Enter number of terms: "))
print(f"Fibonacci series up to {n} terms: {fibonacci_series(n)}")

📘 Conclusion

You now know how to generate the Fibonacci series in Python using both a simple loop and a function-based approach. This is a great beginner-friendly project to understand the basics of Python programming.

If you're learning Python, the Fibonacci series is a must-do program to build logical thinking and hands-on experience with loops and variables.