How to Format Float Values with Python

Floating values can have many decimal places, making them difficult to read and interpret. Formatting allows us to control the number of decimals places displayed and make it consistent throughout our application.

Here are three ways to format float in Python:

1. Using f-strings
2. Using format()
3. Using the % operator
4. Using round()

Method 1: Using f-strings

Python 3.6 introduced f-strings(formatted string literals), which are a more readable and concise way to format strings compared to older methods like the % operator.

# Define a floating-point value
value = 123.45678

formatted_value = f"{value:.3f}"
print("Three decimals:", formatted_value)
# Output: Three decimals: 123.457

formatted_value = f"{value:.2f}"
print("Two decimals:", formatted_value)
# Output: Two decimals: 123.46

formatted_value = f"{value:.1f}"
print("One decimal:", formatted_value)
# Output: One decimal: 123.5

formatted_value = f"{value:.0f}"
print("No decimal:", formatted_value)
# Output: No decimal: 123

Method 2: Using format()

You can use the str.format() method to format floating-point numbers to a specific number of decimal places or in a specific format.

Formatting with two decimal places

value = 123.45678

formatted_value = "{:.2f}".format(value)

print(formatted_value)
# Output: 123.46

print(type(formatted_value))
# Output: <class 'str'>

The output returns a string. To convert the output to a float, use the float() function.

print(float(formatted_value))
# Output: 123.46

print(type(float(formatted_value)))
# Output: <class 'float'>

Formatting with one decimal place

value = 123.45678

formatted_value = "{:.1f}".format(value)

print(float(formatted_value))
# Output: 123.5

Method 3: Using the % Operator

The % operator is an older way of formatting strings. It can also be used for floats and works similarly to the format() method.

# Define a floating-point value
value = 123.45678

# Format the value to two decimal places
formatted_value = "%.2f" % value
print(formatted_value)
# Output: 123.46

# Format the value to one decimal place
formatted_value = "%.1f" % value
print(formatted_value)
# Output: 123.5

# Format the value to no decimal places
formatted_value = "%d" % value
print(formatted_value)
# Output: 123

Method 4: Using the round()

The round() function returns the floating-point number rounded off to the given digits after the decimal point.

It’s important to note that, if you want a string representation, you must convert it.

# Define a floating-point value
value = 123.45678

formatted_value = round(value, 3)
print("Three decimals:", formatted_value)
# Output: 123.457

formatted_value = round(value, 2)
print("Two decimals:", formatted_value)
# Output: 123.46

formatted_value = round(value, 1)
print("One decimal:", formatted_value)
# Output: 123.5

That’s all!

Krunal Lathiya

With a career spanning over eight years in the field of Computer Science, Krunal’s expertise is rooted in a solid foundation of hands-on experience, complemented by a continuous pursuit of knowledge.