Python Set clear() Method

Q: How do I empty a set in Python?

Call `my_set.clear()`. It removes every element in place and keeps the same set object.

Q: What is the difference between clear() and set()?

`clear()` empties the existing set, while `s = set()` binds the name to a brand-new empty set and leaves the old one unchanged for other references.

Q: Does clear() return anything?

No. It returns `None`, so do not assign its result back to the variable.

By Yogesh Sharma (LinkedIn) · Every code example is run and checked on Python 3.13 (how we test) · Last updated 21 Oct 2026

Short answer

set.clear() removes all elements from the set in place and returns None. The set object still exists afterwards, but it is empty.

Use clear() when you want to reuse the same set object, for example resetting a collection of seen items at the start of each round in a game. Because it works in place, every variable that refers to that set sees the change.

If you only need to remove some elements, use remove(), discard() or pop(). Understanding the difference between changing an object and rebinding a name is easier after reading about copying data.

Quick facts
Syntax	`my_set.clear()`
Parameters	None
Returns	`None` (the set is emptied in place)
Time complexity	O(n) in the number of elements

How set.clear() works

After the call the set has length 0 and prints as set(). Calling clear() on an already empty set is fine and does nothing.

Python

cart = {"pen", "book"}
cart.clear()
print(cart)
print(len(cart))

clear() vs assigning set() vs del

clear() empties the existing object. Writing s = set() makes the name point to a new empty set, and any other name that referred to the old one still sees the old contents. del s removes the name itself, so using it later raises NameError.

Python

a = {1, 2, 3}
b = a          # same set object
a = set()      # a now points to a new set
print(sorted(b))

c = {1, 2, 3}
d = c
c.clear()      # the shared object is emptied
print(d)

Code	Effect on the object	Other names for it
`s.clear()`	Emptied in place	See the empty set
`s = set()`	Old object untouched	Still see old items
`del s`	Name removed	Still see old items
`s -= s`	Emptied in place	See the empty set
`s.pop()` in a loop	Emptied one by one	See the empty set

Examples you can run

Press Run, then edit the code and run it again.

Reset a set between rounds

The same set object is reused for each round.

Reset a set between rounds

seen = set()
for round_words in [["a", "b"], ["c"]]:
    seen.clear()
    seen.update(round_words)
    print(sorted(seen))

Expected output['a', 'b']
['c']

clear() affects every reference

Both names point to one set, so clearing through one empties it for both.

clear() affects every reference

original = {1, 2, 3}
alias = original
original.clear()
print(alias)
print(alias is original)

Expected outputset()
True

Common mistakes

Using the return value

✗ Wrong

s = {1, 2}
s = s.clear()
print(s)

None

✓ Right

s = {1, 2}
s.clear()
print(s)

clear() returns None. Call it on its own line and keep using the same name.

Expecting clear() to delete the variable

✗ Wrong

s = {1, 2}
s.clear()
s.add(3)
del s
print(s)

NameError: name 's' is not defined

✓ Right

s = {1, 2}
s.clear()
s.add(3)
print(s)

clear() only removes the elements. The set is still usable afterwards. Use del only if you want the name gone.

Python Set clear() Method: questions people ask

How do I empty a set in Python?

Call my_set.clear(). It removes every element in place and keeps the same set object.

What is the difference between clear() and set()?

clear() empties the existing set, while s = set() binds the name to a brand-new empty set and leaves the old one unchanged for other references.

Does clear() return anything?

No. It returns None, so do not assign its result back to the variable.

Keep learning

Step-by-step lessons:
Python Sets Copying Lists and Dicts

More in set methods:
Python Set add() Method Python Set remove() Method Python Set discard() Method Python Set pop() Method Python Set union() Method Python Set intersection() Method Python Set difference() Method Python Set symmetric_difference() Method See all →