Python Program to Find Volume of Cylinder

To find the volume of a cylinder in Python, use the formula volume = 3.1416 * radius ** 2 * height and write a program that takes radius and height as inputs and calculates this value.

Examples

Inputradius = 1, height = 1

OutputVolume of cylinder: 3.1416

Inputradius = 3, height = 5

OutputVolume of cylinder: 141.372

Inputradius = 0, height = 10

OutputVolume of cylinder: 0.0

How to Think About It

To find the volume of a cylinder, first understand that the volume is the area of the circular base times the height. The base area is calculated using the formula for the area of a circle, which is pi times radius squared. Then multiply this area by the height to get the volume.

Algorithm

1

Get the radius of the cylinder from the user

2

Get the height of the cylinder from the user

3

Calculate the base area using pi times radius squared

4

Multiply the base area by the height to get the volume

5

Display the volume

Code

python

radius = float(input('Enter the radius of the cylinder: '))
height = float(input('Enter the height of the cylinder: '))
pi = 3.1416
volume = pi * radius ** 2 * height
print(f'Volume of cylinder: {volume}')

Output

Enter the radius of the cylinder: 3
Enter the height of the cylinder: 5
Volume of cylinder: 141.372

Dry Run

Let's trace the example where radius = 3 and height = 5 through the code

1

Input radius

User enters radius = 3

2

Input height

User enters height = 5

3

Calculate volume

volume = 3.1416 * 3 ** 2 * 5 = 3.1416 * 9 * 5 = 141.372

4

Print result

Output: Volume of cylinder: 141.372

Step	Operation	Value
1	radius input	3
2	height input	5
3	volume calculation	141.372
4	print output	Volume of cylinder: 141.372

Why This Works

Step 1: Calculate base area

The base area of the cylinder is a circle, so we use pi * radius ** 2 to find it.

Step 2: Multiply by height

Volume is base area times height, so multiply the area by height to get the volume.

Step 3: Display the volume

Print the calculated volume so the user can see the result.

Alternative Approaches

Using math.pi constant

python

import math
radius = float(input('Enter radius: '))
height = float(input('Enter height: '))
volume = math.pi * radius ** 2 * height
print(f'Volume of cylinder: {volume}')

This uses the built-in math module for a more precise value of pi.

Using a function to calculate volume

python

def cylinder_volume(r, h):
    pi = 3.1416
    return pi * r ** 2 * h
radius = float(input('Radius: '))
height = float(input('Height: '))
print(f'Volume of cylinder: {cylinder_volume(radius, height)}')

Encapsulates the calculation in a function for reuse and clarity.

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

Time Complexity

The calculation involves a fixed number of arithmetic operations, so it runs in constant time.

Space Complexity

Only a few variables are used to store inputs and the result, so space usage is constant.

Which Approach is Fastest?

All approaches run in constant time; using math.pi is slightly more accurate but has negligible performance difference.

Approach	Time	Space	Best For
Fixed pi value	O(1)	O(1)	Simple, quick calculations
math.pi constant	O(1)	O(1)	More accurate results
Function encapsulation	O(1)	O(1)	Code reuse and clarity