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Python Assignment Operators

Assignment operators are shortcuts for changing a variable using its own value, like saying 'add 5 to my score'. Instead of writing the score twice, you write it once with a plus-equals.

In this page:

  1. Basic Assignment
  2. Add and Subtract Assignment
  3. Multiply and Divide Assignment
  4. Floor Divide and Modulo Assignment
  5. Exponent and Bitwise Assignment
Syntax
python 
variable = value
variable += value  # also -=, *=, /=, //=, %=, **=

Basic Assignment

The plain = operator binds the name on the left to the value on the right — this is assignment, not mathematical equality, and confusing it with == is one of the most common early Python mistakes.

Example: Basic Assignment

python 
x = 5
print(x)

Add and Subtract Assignment

+= adds a value to a variable and stores the result back in that same variable in one step, so count += 1 is shorthand for count = count + 1; -= does the same for subtraction.

Example: Add and Subtract Assignment

python 
count = 10
count += 1  # same as count = count + 1
print(count)
count -= 2  # same as count = count - 2
print(count)

Multiply and Divide Assignment

*= and /= apply the same "do the operation, then reassign" pattern to multiplication and division, letting you update a running total or scale a value without retyping the variable name twice.

Example: Multiply and Divide Assignment

python 
total = 5
total *= 3  # same as total = total * 3
print(total)
total /= 3  # same as total = total / 3
print(total)

Floor Divide and Modulo Assignment

//= performs floor division and reassigns the result, while %= computes the modulo remainder and reassigns it — both are shorthand forms that come up often when tracking counters or wrapping values within a fixed range.

Example: Floor Divide and Modulo Assignment

python 
n = 17
n //= 5  # floor division: n = n // 5
print(n)
m = 17
m %= 5  # modulo: m = m % 5
print(m)

Exponent and Bitwise Assignment

**= raises a variable to a power and reassigns the result, and bitwise compound operators like &= and |= apply the same shorthand pattern to bit-level operations — all follow the identical "operate then store" logic as +=.

Example: Exponent and Bitwise Assignment

python 
x = 2
x **= 3  # exponent: x = x ** 3
print(x)
flags = 1
flags &= 3  # bitwise AND: flags = flags & 3
print(flags)
Related Topics

Python Bitwise Operators · Python Logical Operators · Python Relational Operators · Python Arithmetic Operators

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Common Mistakes
  1. Writing x =+ 1 instead of x += 1, which just assigns +1 to x.
  2. Using += on a name that has not been defined yet, e.g. total += 5, which raises NameError.
  3. Using += on a list expecting a copy: b = a; b += [1] mutates a too since both names refer to one list.
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