Python bool() Function

Converts a value to a boolean value


The bool() function converts a value to a boolean value i.e. one of True or False.

If the value is not specified, the method returns False.



Python bool() function parameters
valueOptionalAny object (like Number, List, String etc.),
Any expression (like x > y, x in y).

Falsy Values

In Python, everything is considered True, except following values.

  • Constants defined to be false: None and False.
  • Zero of any numeric type: 0, 0.0, 0j, Decimal(0), Fraction(0, 1)
  • Empty sequences and collections: '', (), [], {}, set(), range(0)


Here are some examples that will shed some light on how this function works.

# bool() on falsy values
print(bool(0))			# Prints False
print(bool([]))			# Prints False
print(bool(0.0))		# Prints False
print(bool(None))		# Prints False
print(bool(0j))			# Prints False
print(bool(range(0)))	# Prints False
# bool() on truthy values
print(bool(1))			# Prints True
print(bool([0]))		# Prints True
print(bool([1, 2]))		# Prints True
print(bool(10))			# Prints True
print(bool(3+4j))		# Prints True
print(bool(range(2)))	# Prints True