In this Python tutorial, we will see **how to find the sum of the list in Python** using different methods with demonstrative examples.

A list in Python is an ordered sequence of items that can contain a mix of different data types, including numbers, strings, and other lists. Lists are mutable, meaning we can change their elements. They are defined by enclosing a comma-separated sequence of elements within square brackets **[]**.

For example, we a have list of numbers:

`Numbers = [4, 5, 8, 1, 0, 2, 6, 9]`

What if we want to sum of all these numbers.

## The sum of the list in Python

There are various ways to find **the sum of the list in Python**. They are:

- the sum() Function
- for Loop
- List Comprehension
- while Loop
- Using Recursion Function

We will see them one by one using illustrative examples.

### The sum of the list in Python using the sum() function

The simplest way to find the sum of a list in Python is by using the built-in **sum() function**.

For example, Suppose we have a list of the tallest buildings in New York City, measured in feet: Here, the **sum() function** computes the total height of the tallest buildings in New York City. The function accepts an iterable (like our list) and adds up all the numbers in the iterable.

```
NYC_buildings = [1454, 1250, 1046, 1046, 1007]
total_height = sum(NYC_buildings)
print('The total height of NYC buildings(in feet) will be: ',total_height)
```

**The output is**:

`The total height of NYC buildings(in feet) will be: 5803`

This way we can use the **sum() function** to find the sum of the list in Python.

### The sum of the Python list using for loop

We can also use a **for loop** in Python to calculate the sum of elements in a list.

Here’s an example where we find the sum of the populations (in millions) of the five most populous states in the USA which is stored in a form of a Python list. In this case, we iterate over each population figure in the Python list and add it to the running total.:

```
# California, Texas, Florida, New York, Pennsylvania
populations = [39.5, 29.5, 21.8, 20.0, 19.9]
total_population = 0
for population in populations:
total_population += population
print(total_population)
```

**The Output is**:

`130.7`

This way we can use **for loop** to find the sum of the list in Python.

### The sum of the list in Python using list comprehension

List comprehension in Python is a compact way to process all elements in a list.

Let’s see how to use **list comprehension** with a Python list of the lengths (in miles) of the five longest rivers in the US: Here, the sum is computed on the fly within the **list comprehension** statement.

```
# Missouri, Mississippi, Yukon, etc.
US_river_lengths = [2530, 2460, 2320, 2170, 2078]
total_length = sum(river_length for river_length in US_river_lengths)
print('The total length of the rivers(in miles) is: ', total_length)
```

**The output is**:

`The total length of the rivers(in miles) is: 11558`

This way we can use the **list comprehension** to find the sum of the list in Python.

### The sum of the list in Python using while loop

The **while loop** is another control flow statement in Python that can be used to find the sum of a list.

For example, consider the case where we want to find the sum of the areas (in sq miles) of the top five largest states in the U.S which stored in the form of a Python List: In this case, we loop through each state’s area in the Python list and add it to the total until we’ve covered all elements.

```
# Alaska, Texas, California, Montana, New Mexico
largest_states = [663267, 570641, 268596, 261231, 195303]
total_area = 0
i = 0
while i < len(largest_states):
total_area += largest_states[i]
i += 1
print('Total areas (in sq miles) of the top five largest states in the U.S:', total_area)
```

**The output is**:

`Total areas (in sq miles) of the top five largest states in the U.S: 1959038`

This way we can use **while loop** to find the sum of the list in Python.

### The sum of the list in Python using recursion function

If we want to practice** recursion function**, we can use it to find the sum of a list in Python.

Here’s an example where we find the sum of the number of National Parks in the five states with the most National Parks which is stored in a Python list:

This **recursive function** in Python takes a list as input and returns the sum of the elements. It adds the first element of the Python list to the sum of the rest of the list until the list is empty.

```
# California, Alaska, Utah, Colorado, Arizona
national_parks = [24, 13, 10, 8, 7]
def find_sum(lst):
if len(lst) == 0:
return 0
else:
return lst[0] + find_sum(lst[1:])
total_parks = find_sum(national_parks)
print(total_parks)
```

**The Output is**:

`Total numbers of parks: 62`

This way we can use** the recursion function **in Python to find the sum of the list.

## Conclusion

Python offers a multitude of methods **to find the sum of a list**. From built-in functions like **sum()**, loops such as **for and while**, **list comprehension**, and **recursion function** methods. Each method has its unique use cases and benefits. The method we choose should align with our specific requirements, our data structure, and our task’s performance needs.

You may like also like to read:

- How to Sum Elements in List in Python using For Loop
- How to Add Numbers in a List in Python Without Sum
- How to find the size of a Python list

I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.