Python String to Float[Explained with Code Examples] - JSON Viewer

Python String to Float[Explained with Code Examples]

Python String to Float Conversion is a frequent task that is encountered in programming when dealing with numerical data that is represented as strings.

This conversion is essential for a programmer who is working with numerical datas for arithmetical and logical operations.

Introduction to String and Float Datatypes:

A string is a data type in python having values such as numbers, Alphabets and other characters. On the other hand is a numerical data type having decimal value.

We can see an example of string type

my_string = "Goom"
#output <class 'str'>

An example of float data type

my_float = 5.0
#output <class 'float'>

Convert Python String to Float

Python provides and inbuilt function called float(), By using this function we can convert the string data type to float data type


my_string = "100"
my_float = float(my_string)
#output <class 'float'>

From the above example, a variable my_string has a string value 100. In the second line of code we can see that the string is converted to float with the inbuilt function float() and it is stored into a variable called my_float.

By printing the type of that variable we can see that it is changed to float.

Arithmetic calculations using Python string-to-float conversions

my_num1 = "5.6"
my_num2 = "4.2"
my_result = float(my_num1) + float(my_num2)
#output is 9.8

In the first stage, two string variables called my_num1 and my_num2 that each contain a string representation of a number are defined.

To convert these strings into floating-point numbers, the built-in float() method is used. This function accepts a string parameter and outputs a floating-point value in its place. Float(my_num1) returns a float value of 5.6 in this case, but float(my_num2) returns a float value of 4.2.

The two float values are combined with the + operator in the final step, and the result is then saved in the variable my_result.

The print() method is then used to display the value of my_result, which is 9.8.

Calculating the sum of string numbers in a list

list_of_numbers = [ "2.0", "50.12", "12.5", "200.0" ]
result = 0.0
for i in list_of_numbers:
result += float(list_of_numbers)
#output is 264.62

From the above example, a variable named list_of_numbers is having four string values and each showing a number. The next step is to set the value of the result variable to 0.0. The list_of_numbers’ elements are then iterated over in a for loop.

The float() function is used inside the loop to convert each string element to a floating-point number, and the resulting float value is added to the result variable using the += operator.

After the loop is finished, the final value of result is the total of all the float values that were created from the list_of_numbers’ initial string values.

The output value is finally shown using the print() method.

Calculate the string of numbers from a dictionary to float

my_dict = {"num1": "3.14", "num2": "2.0", "num3": "7.5"}
for num in my_dict:
my_dict[num] = float(my_dict[num])


{'num1': 3.14, 'num2': 2.0, 'num3': 7.5}

The keys “num1,” “num2,” and “num3” have string values in the dictionary my_dict in this example.

Each key in the dictionary is iterated through using a loop. My_dict[num], where num is the key in each iteration of the loop, allows us to get the string value for each key.

The string value is then converted to a float value using the float() function, and the updated float value is then returned to the same entry in the dictionary using the syntax my_dict[num] = float(my_dict[num]).

In order to confirm that the string values have been successfully transformed into float values, we print the updated dictionary using print(my_dict).


In conclusion, the float() method in Python can be used to transform string values into floating-point numbers. This conversion can be helpful when working with numerical data that is entered as a string or stored as a string in a file or database.

We may also use a loop or list comprehension to change the string values in a list or dictionary of string values using the float() method.

After converting the data to float values, we may use the data to carry out more challenging mathematical operations, including calculating the mean or standard deviation of a group of integers.

Overall, working with numerical data in a flexible and effective manner is made simple by Python’s ability to translate strings into float values.