Convert String to Float in Python

In this tutorial, we will look at how to convert a string in Python to a float value, that is, float datatype with the help of some examples.

How to convert string to float in Python?

You can use the Python built-in float() function to convert a string to a float value in Python. The following is the syntax –

# convert string s to float
float(s)

It returns the passed string as a floating-point value. Note that if the passed string does not represent a numeric value, it will raise an error.

Examples

Let’s look at some examples of using the above syntax to convert a string to a floating-point value.

First, let’s apply the float() function on a string containing a real number with a decimal part, for example, “150.75”.

# string storing a float number
s = "150.75"
# convert string to float
num = float(s)
# display the number and its type
print(num)
print(type(num))

Output:

150.75
<class 'float'>

You can see that we get 150.75 as a float value.

What happens if you pass an integer number as a string to the float() function? Let’s find out.

# string storing an integer
s = "150"
# convert string to float
num = float(s)
# display integer and its type
print(num)
print(type(num))

Output:

150.0
<class 'float'>

We get 150.0 as a float point number after conversion.

If you want to convert the above string to an integer in Python, use the int() function instead.

# string storing an integer
s = "150"
# convert string to int
num = int(s)
# display number and its type
print(num)
print(type(num))

Output:

150
<class 'int'>

We get the string as an integer.

What happens if you pass a non-numeric string to the float() function? Let’s find out.

# string with text
s = "cat"
# convert string to float
num = float(s)
# display number and its type
print(num)
print(type(num))

Output:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Input In [4], in <module>
      2 s = "cat"
      3 # convert string to float
----> 4 num = float(s)
      5 # display number and its type
      6 print(num)

ValueError: could not convert string to float: 'cat'

As expected, we get an error because the passed string cannot be represented as a floating-point number.

You might also be interested in –

1. Extract Numbers From String in Python
2. Python – Check if String Contains Only Numbers
3. Python Tuple to Integer