What is the difference between the data types decimal and float in Python?

float uses a binary floating-point representation, which can lead to inaccuracies when working with decimal fractions due to the nature of binary conversion. decimal stores decimal numbers exactly, without rounding, making it preferable for financial calculations and other tasks requiring high precision. decimal is slower and consumes more memory than float.

# Example with float
a = 0.1 + 0.1 + 0.1
print(f"{a=}") # a=0.30000000000000004

# Example with decimal
from decimal import Decimal
b = Decimal('0.1') + Decimal('0.1') + Decimal('0.1')
print(f"{b=}") # b=Decimal('0.3')

Attribute	float	decimal
Precision	Approximate (binary representation)	Exact (decimal representation)
Speed	Faster	Slower
Memory	Less	More
Use case	Scientific calculations where precision is not critical	Financial calculations, precise computations