Python Program to Convert Kilometers to Miles

You can convert kilometers to miles in Python by multiplying the kilometers value by 0.621371. For example, miles = kilometers * 0.621371.

Examples

Input0

Output0.0 miles

Input5

Output3.106855 miles

Input100

Output62.1371 miles

How to Think About It

To convert kilometers to miles, you multiply the number of kilometers by the conversion factor 0.621371 because 1 kilometer equals approximately 0.621371 miles. This simple multiplication gives the equivalent distance in miles.

Algorithm

1

Get the distance in kilometers from the user

2

Multiply the kilometers by 0.621371 to convert to miles

3

Display the result in miles

Code

python

kilometers = float(input("Enter distance in kilometers: "))
miles = kilometers * 0.621371
print(f"{kilometers} kilometers is equal to {miles} miles")

Output

Enter distance in kilometers: 5
5.0 kilometers is equal to 3.106855 miles

Dry Run

Let's trace the input 5 kilometers through the code

1

Input kilometers

User inputs 5, so kilometers = 5.0

2

Calculate miles

miles = 5.0 * 0.621371 = 3.106855

3

Print result

Output: '5.0 kilometers is equal to 3.106855 miles'

kilometers	miles
5.0	3.106855

Why This Works

Step 1: Get input

The program asks the user to enter the distance in kilometers using input() and converts it to a floating-point number with float().

Step 2: Convert kilometers to miles

It multiplies the kilometers by the fixed conversion factor 0.621371 to get the equivalent miles.

Step 3: Display output

The program prints the result using an f-string to show the original kilometers and the converted miles clearly.

Alternative Approaches

Using a function

python

def km_to_miles(km):
    return km * 0.621371

km = float(input("Enter kilometers: "))
miles = km_to_miles(km)
print(f"{km} kilometers = {miles} miles")

This approach organizes the conversion into a reusable function, making the code cleaner and easier to maintain.

Using a constant variable

python

CONVERSION_FACTOR = 0.621371
km = float(input("Kilometers: "))
miles = km * CONVERSION_FACTOR
print(f"{km} km is {miles} miles")

Using a named constant improves readability and makes it easy to update the conversion factor if needed.

Complexity: O(1) time, O(1) space

Time Complexity

The program performs a single multiplication and input/output operations, so it runs in constant time.

Space Complexity

It uses a fixed amount of memory for variables, so space complexity is constant.

Which Approach is Fastest?

All approaches run in constant time and space; using a function or constant variable mainly improves code clarity, not speed.

Approach	Time	Space	Best For
Direct calculation	O(1)	O(1)	Simple quick conversion
Function method	O(1)	O(1)	Reusable code in larger programs
Constant variable	O(1)	O(1)	Readability and easy updates