Find average of a list in python

Last Updated : 22 Sep, 2026

We are given a list of numbers and need to find the average of its elements. For example, a = [10, 20, 30, 40], the sum is 100 and the number of elements is 4, so the average is 25.0.

Python 
numbers = [10, 20, 30, 40]
total = sum(numbers)
count = len(numbers)
average = total / count
print("Average:", average)

Using sum()

sum() function calculates the total of the list elements, while len() returns the number of elements.

Python 
a = [2, 4, 6, 8, 10]
avg = sum(a) / len(a)
print(avg)

Output
6.0

Explanation:

  • sum(a) calculates the sum of all elements.
  • len(a) returns the number of elements.
  • sum(a) / len(a) calculates the average.

Using a Loop

A for loop can be used to calculate the sum manually and then divide it by the number of elements.

Python 
a = [2, 4, 6, 8, 10]
total = 0

for val in a:
    total += val

avg = total / len(a)
print(avg)

Output
6.0

Explanation:

  • total is initialized to 0.
  • The loop adds each element to total.
  • len(a) gives the number of elements.
  • total / len(a) calculates the average.

Using the Statistics Library

statistics.mean() function directly calculates the arithmetic mean of the values.

Python 
import statistics
a = [2, 4, 6, 8, 10]

avg = statistics.mean(a)
print(avg)

Output
6

Explanation:

  • statistics.mean(a) calculates the arithmetic mean.
  • The result is 6 for the given list.

Using numpy.average()

numpy.average() function calculates the average of the elements and is useful when working with numerical data.

Python 
import numpy

a = [2, 4, 6, 8, 10]
avg = numpy.average(a)

print(avg)

Output
6.0

Explanation:

  • np.average() calculates the average of the elements.
  • It returns the result as a floating-point value.

Handling an Empty List

An empty list has no elements, so its average cannot be calculated.

Python 
a = []

if a:
    avg = sum(a) / len(a)
    print(avg)
else:
    print("List is empty")

Output
List is empty

Explanation:

  • if a checks whether the list contains elements.
  • The average is calculated only when the list is not empty.
  • The else block handles an empty list.
  • This prevents a ZeroDivisionError.

Note: If the list is empty, sum(a) / len(a) raises a ZeroDivisionError because len(a) is 0. Check whether the list contains elements before calculating the average.

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