Pyfied
Log in
ReferenceBuilt-in functions

Python abs() Function

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

Short answer
abs(x) returns the absolute value of a number: its distance from zero, so abs(-7) is 7.

The absolute value drops the sign of a number. It answers questions like "how far apart are these two values?" without caring which one is larger: the gap between a temperature of 18 and 25 is 7 either way.

Python's abs() works on integers and floats and also on complex numbers, where it gives the magnitude. For your own classes you can support it by defining __abs__(), one of the special methods.

Syntaxabs(x)
Parametersx: an int, float, complex number, or an object that defines __abs__()
ReturnsA non-negative number of the same kind (a float for a complex input)
RaisesTypeError for strings, lists and other non-numeric values
Time complexityO(1)

How abs() treats ints, floats and complex numbers

For a negative int or float, abs() flips the sign. For a positive number or zero it returns the same value. The type is preserved: an int stays an int and a float stays a float.

For a complex number a + bj, abs() returns the length of the vector from the origin, sqrt(a*a + b*b), as a float. That is why abs(3 + 4j) equals 5.0.

Python 
print(abs(-12))
print(abs(-0.75))
print(abs(3 + 4j))





      
      
    

    

    
    

      
Using abs() to measure differences and tolerances

      
Two everyday jobs make abs() worth knowing. The first is the distance between two numbers: abs(a - b). The second is comparing floats safely. Floats store tiny rounding errors, so 0.1 + 0.2 == 0.3 is False; checking that abs(x - y) is below a small tolerance is more reliable. For serious numeric work, math.isclose() from the math module does this for you.



  

    Python
    

      
      
      
      
    

  

  
total = 0.1 + 0.2
print(total == 0.3)
print(abs(total - 0.3) < 1e-9)

  
  
  
  

    
      
      
    
    
  

  





      
      
    

    
    
    

      
abs() vs math.fabs() vs negation

      
      
      
      

        
        
ToolInput typesReturn type for an int input

        
abs(x)int, float, complex, custom __abs__int
math.fabs(x)Real numbers onlyfloat
-xAny numberFlips the sign; positive numbers become negative
max(x, -x)Real numbersSame as abs(x) but slower and less clear

      

      
    

    
    

    
    

      
Examples you can run

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

      
      

        
Absolute value of different numbers

        
Sign is dropped; zero stays zero.

        

  

    Absolute value of different numbers
    

      
      
      
      
    

  

  
print(abs(-7), abs(-3.5), abs(0), abs(12))

  
  
  
  

    
      
      
    
    
  

  
Expected output7 3.5 0 12




      

      
      

        
Distance between two readings

        
abs(a - b) gives the gap regardless of order.

        

  

    Distance between two readings
    

      
      
      
      
    

  

  
morning = 18
evening = 25
print(abs(morning - evening))
print(abs(evening - morning))

  
  
  
  

    
      
      
    
    
  

  
Expected output7
7




      

      
      

        
Find the closest value

        
Use abs() as the key of min() to pick the item nearest a target.

        

  

    Find the closest value
    

      
      
      
      
    

  

  
prices = [80, 95, 130, 210]
target = 100
print(min(prices, key=lambda p: abs(p - target)))

  
  
  
  

    
      
      
    
    
  

  
Expected output95




      

      
      

        
Magnitude of a complex number

        
The result is a float.

        

  

    Magnitude of a complex number
    

      
      
      
      
    

  

  
z = 3 + 4j
print(abs(z))

  
  
  
  

    
      
      
    
    
  

  
Expected output5.0




      

      
    

    

    
    

      
Common mistakes

      
      

        
Passing a string

        

          
✗ Wrong
balance = "-50"
print(abs(balance))
TypeError: bad operand type for abs(): 'str'

          
✓ Right
balance = "-50"
print(abs(int(balance)))

        

        
Convert the text to a number first.

      

      
      

        
Calling abs() on a list

        

          
✗ Wrong
changes = [-3, 5, -1]
print(abs(changes))
TypeError: bad operand type for abs(): 'list'

          
✓ Right
changes = [-3, 5, -1]
print([abs(c) for c in changes])

        

        
abs() takes one number. Apply it to each item with a comprehension or map().

      

      
      

        
Comparing floats with ==

        

          
✗ Wrong
x = 0.1 + 0.2
print(x == 0.3)
Prints `False` even though the maths says they are equal.

          
✓ Right
x = 0.1 + 0.2
print(abs(x - 0.3) < 1e-9)

        

        
Compare with a tolerance using abs().

      

      
    

    

    
    

      
Python abs() Function: questions people ask

      
How do I get the absolute value in Python?
Use the built-in abs() function, for example abs(-5) returns 5. It needs no import.
Does abs() work with floats and complex numbers?
Yes. For floats it drops the sign, and for complex numbers it returns the magnitude as a float, so abs(3 + 4j) is 5.0.
What is the difference between abs() and math.fabs()?
abs() keeps the input type and also accepts complex numbers, while math.fabs() always returns a float and accepts only real numbers.

    

    

    
    

      
Keep learning

      
Step-by-step lessons:
Python NumbersPython math and statisticsPython Operators

      
Related:
Python round() FunctionPython pow() FunctionPython min() FunctionPython max() Function

      
More in built-in functions:
Python print() FunctionPython len() FunctionPython range() FunctionPython type() FunctionPython int() FunctionPython float() FunctionPython str() FunctionPython input() Function See all →