Which is the fastest way to reverse a list in Python?

nums.reverse() is the fastest because it doesn't copy the list. In a test with a million numbers it took about 0.5 ms, while nums[::-1] took about 4 ms.

How do you sort a list in reverse order in Python?

Use sorted(nums, reverse=True) for a new list, or nums.sort(reverse=True) to change the list. That sorts from largest to smallest, which is different from just flipping the order.

How do you reverse the words in a sentence in Python?

Split the sentence into words, reverse them and join them again: " ".join(reversed(sentence.split())). "I love Python" becomes "Python love I".

How do you reverse a string in Python?

Strings have no reverse() method, so use slicing: "hello"[::-1] returns 'olleh'. "".join(reversed(text)) gives the same result.

What is the difference between reverse(), reversed() and [::-1]?

reverse() flips the list itself. [::-1] returns a new reversed list. reversed() returns an iterator for loops, which you can turn into a list with list(reversed(nums)).

Why does reverse() return None in Python?

reverse() changes the list in place and returns None, so nums = nums.reverse() leaves you with None. Call nums.reverse() on its own line, or use nums = nums[::-1].

4Geeks chosen to deliver AI education in the Bahamas alongside Harvard, Oxford, and Columbia.See more

How to Reverse a List in Python?

Q: How do you reverse a list in Python?

Call nums.reverse() to reverse the list itself, or use nums[::-1] to get a reversed copy and keep the original. To loop backwards without copying, use reversed(nums).

Reverse a list in place or as a copy, loop backwards, reverse strings and sentences and avoid the reverse() returns None trap.

6 min readLast updated Nov 10, 2026

How do you reverse a list in Python?

Short answer: call nums.reverse() to reverse the list itself, or use nums[::-1] to get a reversed copy and keep the original. To loop backwards without making a copy, use reversed(nums).

python

nums = [1, 2, 3, 4, 5]
 
nums.reverse()
print(nums)          # [5, 4, 3, 2, 1]
 
print(nums[::-1])    # [1, 2, 3, 4, 5]  a new list

reverse() returns None, so never write nums = nums.reverse(). Strings have no reverse(), but "hello"[::-1] returns 'olleh'.

reverse() changes the list itself, [::-1] returns a new reversed list and also works with strings.

Every way to reverse in Python

What you want	Code	Changes the original	Returns
Reverse the list itself	`nums.reverse()`	Yes	`None`
A reversed copy	`nums[::-1]`	No	A new list
Loop backwards	`for n in reversed(nums):`	No	An iterator
A reversed copy from the iterator	`list(reversed(nums))`	No	A new list
Sort from largest to smallest	`sorted(nums, reverse=True)`	No	A new sorted list
Reverse a string	`"hello"[::-1]` or `"".join(reversed("hello"))`	No (strings can't change)	`'olleh'`
Reverse the words of a sentence	`" ".join(reversed(text.split()))`	No	`'Python love I'`
Reverse a tuple	`(1, 2, 3)[::-1]`	No	`(3, 2, 1)`
Count down	`range(5, 0, -1)`	—	`5, 4, 3, 2, 1`

Reverse a list in place with reverse()

reverse() flips the order of the list you call it on. It doesn't create a new list and it returns None:

python

nums = [1, 2, 3, 4, 5]
result = nums.reverse()
 
print(nums)     # [5, 4, 3, 2, 1]
print(result)   # None

Every variable that points to that list sees the change:

python

a = [1, 2, 3]
b = a
a.reverse()
print(b)        # [3, 2, 1]

Use it when you don't need the original order any more. It is also the fastest option: in a test with a million numbers, reverse() took about 0.5 ms and [::-1] about 4 ms.

Career · AI Engineering

You already handle Python lists, now build with AI

From zero to junior AI Engineer: Python, data, AI agents and RAG with mentors and real projects.

I want more information See the program

Get a reversed copy with slicing [::-1]

The slice [start:stop:step] with a step of -1 walks the list from the end to the start and builds a new list:

python

nums = [1, 2, 3, 4, 5]
backwards = nums[::-1]
 
print(backwards)   # [5, 4, 3, 2, 1]
print(nums)        # [1, 2, 3, 4, 5]  unchanged

With other steps you can also skip items: [1, 2, 3, 4, 5][::-2] returns [5, 3, 1].

Loop backwards with reversed()

reversed() returns an iterator that gives the items from the last to the first, without copying the list. It's the best choice for a for loop:

python

for fruit in reversed(["apple", "banana", "cherry"]):
    print(fruit)
# cherry
# banana
# apple

The iterator is not a list, so len() and indexes don't work on it. Wrap it in list() when you need a list: list(reversed(nums)).

Reverse vs sort in reverse order

Reversing flips the current order. Sorting with reverse=True orders the items from largest to smallest:

python

nums = [3, 1, 2]
 
print(nums[::-1])                    # [2, 1, 3]  just flipped
print(sorted(nums, reverse=True))    # [3, 2, 1]  sorted, descending

nums.sort(reverse=True) does the same but changes the list.

Reverse a string in Python

Strings can't be changed, so they have no reverse() method. Use slicing, or join() with reversed():

python

text = "hello"
 
print(text[::-1])                  # olleh
print("".join(reversed(text)))     # olleh

To reverse the order of the words instead of the letters, split the sentence first:

python

sentence = "I love Python"
print(" ".join(reversed(sentence.split())))   # Python love I

A common use is checking palindromes:

python

word = "racecar"
print(word == word[::-1])   # True

Reverse nested lists, tuples and NumPy arrays

python

nested = [[1, 2], [3, 4]]
print(nested[::-1])                  # [[3, 4], [1, 2]]  order of the lists
print([row[::-1] for row in nested]) # [[2, 1], [4, 3]]  each list inside
 
print((1, 2, 3)[::-1])               # (3, 2, 1)
 
import numpy as np
print(np.flip(np.array([1, 2, 3])))  # [3 2 1]

Use AI to reverse and reorder your data

An assistant like ChatGPT, Claude or GitHub Copilot can pick the right method for your case and explain a strange result. These three prompts are ready to copy.

1. Choose a method

In Python I have this list: [paste a short example].
I need it [reversed / sorted from largest to smallest / reversed without changing the original].
Show me the best way and explain why.

2. Explain a result

This Python code: [paste your code]
prints [what you see] and I expected [what you expected].
Explain why and how to fix it.

3. Reverse text

I need to reverse [the letters / the words / each word] of this text in Python: "[your text]".
Show me the code and the result.

Run the code with a short example you can check by eye.

Learn with a mentor

From reversing lists to AI applications

In the 4Geeks AI Engineering career program you start with no experience and finish with AI agents and RAG systems in your portfolio.

Talk to an advisor See the program

Common problems when reversing in Python

What you see	Why it happens	Fix
The list is `None` after `nums = nums.reverse()`	`reverse()` changes the list and returns `None`	Write `nums.reverse()` on its own line, or `nums = nums[::-1]`
`AttributeError: 'str' object has no attribute 'reverse'`	Strings can't be changed in place	`text[::-1]`
`<list_reverseiterator object at 0x...>` when you print	`reversed()` returns an iterator	`list(reversed(nums))`
`TypeError: object of type 'list_reverseiterator' has no len()`	Iterators don't have a length	Use `len(nums)`, or convert with `list()`
Another variable also changed	`reverse()` changes the list every variable points to	Use `nums[::-1]` to keep the original
The list is sorted, not reversed	`sort(reverse=True)` sorts in descending order	Use `reverse()` or `[::-1]` to only flip it
Emoji or accents look broken when reversed	Some characters are made of several code points	Reverse with a library that handles graphemes, such as `regex`

Free download

Reversing in Python in a 2-page cheat sheet

reverse(), [::-1], reversed(), reverse vs sort, strings and sentences, nested lists, tuples and NumPy, common errors and prompts for ChatGPT, Claude or Copilot. Free, in PDF.

How to reverse a list in Python cheat sheet

2 pages · PDF · 4Geeks

Every way to reverse lists and strings in one table
When the original list changes and when it doesn't
Common errors and prompts to solve them with AI

Get it free

Your PDF right away

Frequently asked questions about reversing lists in Python

Want to go from your first Python lists to building AI applications, with real projects and mentors?

See the AI Engineering program

How to Reverse a List in Python?

How do you reverse a list in Python?

Every way to reverse in Python

Reverse a list in place with reverse()

You already handle Python lists, now build with AI

Get a reversed copy with slicing [::-1]

Loop backwards with reversed()

Reverse vs sort in reverse order

Reverse a string in Python

Reverse nested lists, tuples and NumPy arrays

Use AI to reverse and reorder your data

From reversing lists to AI applications

Common problems when reversing in Python

Related guides

Reversing in Python in a 2-page cheat sheet

Frequently asked questions about reversing lists in Python

Which is the fastest way to reverse a list in Python?

How do you sort a list in reverse order in Python?

How do you reverse the words in a sentence in Python?

How do you reverse a string in Python?

What is the difference between reverse(), reversed() and [::-1]?

Why does reverse() return None in Python?

How do you reverse a list in Python?