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Python Dictionary clear() Method

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

Short answer
dict.clear() removes all key-value pairs from a dictionary in place, leaving it empty, and returns None. Every variable that refers to that dictionary sees it become empty.

clear() is the simplest way to reset a dictionary while keeping the same object, for example a cache or a settings store that other parts of your program already hold a reference to. It is one of the basic dictionary methods.

The key point is in place: clear() empties the existing object instead of creating a new one. That is what separates it from d = {}, a difference that causes real bugs when two names point at the same dictionary.

Syntaxmy_dict.clear()
ParametersNone
ReturnsNone
EffectRemoves all items; the dictionary object itself remains
Time complexityO(n)

What dict.clear() does

After clear(), len(d) is 0 and d prints as {}. Calling it on an already empty dictionary is fine and does nothing. It never raises an error for an empty dictionary, unlike popitem().

Python 
cart = {"pen": 2, "book": 1}
print(cart.clear())
print(cart)
print(len(cart))





The first line prints None because clear() returns nothing useful.

      
      
    

    

    
    

      
clear() vs assigning {} vs del

      
Assigning d = {} rebinds the name to a new empty dictionary. Other names that referred to the old dictionary still see the old contents. d.clear() empties the shared object, so every name sees the change. del d removes the name itself, not the contents, and using d afterwards raises NameError.


Remember that b = a does not copy a dictionary; both names refer to the same object. If you need an independent copy before clearing, use dict.copy().

      
      
      

        Three ways to "empty" a dictionary.
        
CodeSame dictionary object kept?Other references see an empty dict?Name still usable?

        
d.clear()YesYesYes
d = {}No, a new one is madeNo, they keep the old dataYes
del dName is removedOnly if no other name holds itNo

      

      
    

    
    
    

      
When to use clear() and when to remove single keys

      
Use clear() to reset caches, state holders or loop accumulators that you reuse. To remove a single entry, use pop() or del d[key] instead. To keep only some entries, a dictionary comprehension building a new dictionary is usually clearer than clearing and re-adding.

      
      
    

    
    

    
    

      
Examples you can run

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

      
      

        
Reset a dictionary after use

        
We reuse the same dictionary for every order by clearing it at the end of each loop.

        

  

    Reset a dictionary after use
    

      
      
      
      
    

  

  
orders = [["pen", "book"], ["ruler"]]
cart = {}
for order in orders:
    for item in order:
        cart[item] = cart.get(item, 0) + 1
    print(len(cart), "item types")
    cart.clear()
print(cart)

  
  
  
  

    
      
      
    
    
  

  
Expected output2 item types
1 item types
{}




      

      
      

        
clear() changes every reference

        
Both names point at the same dictionary, so clearing through one empties both.

        

  

    clear() changes every reference
    

      
      
      
      
    

  

  
a = {"x": 1}
b = a
a.clear()
print(b)

  
  
  
  

    
      
      
    
    
  

  
Expected output{}




      

      
      

        
Assigning {} leaves other references alone

        
a = {} only rebinds the name a; b still holds the old data.

        

  

    Assigning {} leaves other references alone
    

      
      
      
      
    

  

  
a = {"x": 1}
b = a
a = {}
print(a)
print(b)

  
  
  
  

    
      
      
    
    
  

  
Expected output{}
{'x': 1}




      

      
    

    

    
    

      
Common mistakes

      
      

        
Using the return value of clear()

        

          
✗ Wrong
d = {"a": 1}
d = d.clear()
print(d)
None

          
✓ Right
d = {"a": 1}
d.clear()
print(d)

        

        
clear() returns None and empties the dictionary itself. Call it without assigning.

      

      
      

        
Clearing a dictionary you meant to keep

        

          
✗ Wrong
original = {"a": 1}
backup = original
original.clear()
print(backup)
{}  (backup was the same object)

          
✓ Right
original = {"a": 1}
backup = original.copy()
original.clear()
print(backup)

        

        
Make a real copy first with original.copy().

      

      
    

    

    
    

      
Python Dictionary clear() Method: questions people ask

      
How do I empty a dictionary in Python?
Call my_dict.clear(). It removes all items in place. Assigning my_dict = {} also gives an empty dictionary but creates a new object.
What is the difference between clear() and del for a dictionary?
clear() removes the items but keeps the dictionary, while del my_dict deletes the variable name itself.
Does clear() return anything?
No. It returns None.

    

    

    
    

      
Keep learning

      
Step-by-step lessons:
Python DictionariesPython Dictionary MethodsCopying Lists and Dicts

      
Related:
Python Dictionary copy() MethodPython Dictionary pop() MethodPython Dictionary popitem() MethodPython Dictionary update() Method

      
More in dictionary methods:
Python Dictionary get() MethodPython Dictionary items() MethodPython Dictionary keys() MethodPython Dictionary values() MethodPython Dictionary update() MethodPython Dictionary pop() MethodPython Dictionary popitem() MethodPython Dictionary setdefault() Method See all →