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Srinivas Ramakrishna for ItsMyCode

Posted on • Originally published at itsmycode.com on

# Convert String to Float in Python

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In this tutorial, we will take a look at how to convert string to float in Python.

## Convert string to float in Python

Usually, in Python, the user input that we get will be a string when you read the data from the terminal, excel, CSV, or from a web form. We need to convert the string explicitly into the floating-point value before performing any arithmetic operations. Otherwise, Python will throw valueerror.

### `float()` function

The `float()` function is a built-in utility method which takes any object as an input parameter and converts into floating point number.Internally `float()`function calls specified object`__float__ ()` function.

Syntax: float(obj)

The float method accepts only one parameter, which is optional. If you don’t pass any parameter, then the method will return 0.0 as output.

### Example 1 – Convert string to float

``````input= "33.455"
print(input)
print('Before conversion',type(input))

# converting string to float
output = float(input)
print(output)
print('After conversion',type(output))

``````

Output

``````33.455
Before conversion <class 'str'>
33.455
After conversion <class 'float'>
``````

### Example 2 – Default float conversion without any input parameter

``````output = float()
print(output)

# Output
# 0.0

``````

### Example 3 – Convert a String representing integer to a floating-point number

``````# string with integer to float
input= "100"
print(input)
print('Before conversion',type(input))

# converting string to float
output = float(input)
print(output)
print('After conversion',type(output))

``````

Output

``````100
Before conversion <class 'str'>
100.0
After conversion <class 'float'>
``````

### Example 4 – Converting string only with a decimal part to float

``````# string with integer to float
input= ".000123"
print(input)
print('Before conversion',type(input))

# converting string to float
output = float(input)
print(output)
print('After conversion',type(output))

``````

Output

``````.000123
Before conversion <class 'str'>
0.000123
After conversion <class 'float'>
``````

### Example 5 – Converting a string of exponential to float

``````# string with integer to float
input= "1.23e-4"
print(input)
print('Before conversion',type(input))

# converting string to float
output = float(input)
print(output)
print('After conversion',type(output))

``````

Output

``````1.23e-4
Before conversion <class 'str'>
0.000123
After conversion <class 'float'>
``````

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