Round a float DOWN to the nearest Integer in Python

Round a float DOWN to the nearest Integer in Python #

Use the math.floor() method to round a float down to the nearest integer, e.g. result = math.floor(3.999). The math.floor method returns the largest integer less than or equal to the provided number.

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import math


# ✅ round float down to nearest integer using math.floor()

result_1 = math.floor(3.999)
print(result_1)  # 👉️ 3

result_2 = math.floor(3.14)
print(result_2)  # 👉️ 3

result_3 = math.floor(-3.6)
print(result_3)  # 👉️ -4

# --------------------------------------------------

# ✅ round float down to nearest integer using int()

result_4 = int(3.999)
print(result_4)  # 👉️ 3

result_5 = int(3.14)
print(result_5)  # 👉️ 3

result_6 = int(-3.6)
print(result_6)  # 👉️ -3

We used the math.floor() method to round a floating-point number down to the nearest integer.

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import math

print(math.floor(6.99))  # 👉️ 6
print(math.floor(6.01))  # 👉️ 6
print(math.floor(-6.01))  # 👉️ -7

The math.floor method returns the largest integer less than or equal to the provided number.

This is different than the int() class, which rounds towards zero.

Round a float DOWN to the nearest Integer using int() #

Use the int() class to round a float down to the nearest integer, e.g. result = int(3.999). The int() class truncates floating-point numbers towards zero, so it will return an int that represents the number without the decimal places.

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result_1 = int(3.999)
print(result_1)  # 👉️ 3

result_2 = int(3.14)
print(result_2)  # 👉️ 3

result_3 = int(-3.6)
print(result_3)  # 👉️ -3

The int class returns an integer object constructed from the provided number or string argument.

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print(int(-11.1)) # 👉️ -11
print(int(-13.9)) # 👉️ -13

Notice that there is a difference to how math.floor() and int() handle negative numbers:

• math.floor() rounds towards negative infinity
• int() truncates towards zero

Alternatively, you can use the math.trunc() method.

Round a float DOWN to the nearest Integer using math.trunc() #

Use the math.trunc() method to round a float down to the nearest integer, e.g. result = math.trunc(3.999). The math.trunc() method removes the fractional part and returns the integer part of the given number.

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import math


result_1 = math.trunc(3.999)
print(result_1)  # 👉️ 3

result_2 = math.trunc(3.14)
print(result_2)  # 👉️ 3

result_3 = math.trunc(-3.6)
print(result_3)  # 👉️ -3

The math.trunc method takes a number, removes its fractional part and returns its integer part.

The math.trunc() method rounds towards zero.

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import math

print(math.trunc(-9.1))  # 👉️ -9
print(math.trunc(-9.9))  # 👉️ -9

This approach achieves the same result as passing the floating-point number to the int() class.