Different between Float and Doubles in C

In C programming, floating-point numbers are used to represent real numbers with fractional parts. The language provides two variations of floating-point types: float and double. In this article, we will explore the differences between float and double in C, their applications, and considerations for their usage.

Float and Double

Before diving into the specifics, let’s establish a foundation by defining float and double:

  • Float: The float data type in C represents single-precision floating-point numbers. It provides a balance between precision and storage size.
  • Double: The double data type in C represents double-precision floating-point numbers. It offers increased precision but requires more storage.

Storage and Precision Differences

One of the key distinctions between float and double lies in their storage size and the level of precision they provide:

  • Float: Float typically occupies 4 bytes (32 bits) of memory and offers a precision of around 6 decimal places.
  • Double: Double, on the other hand, occupies 8 bytes (64 bits) of memory and provides a precision of about 15 decimal places.

Range and Accuracy

Another aspect to consider is the range and accuracy of float and double:

  • Float: Float can represent values ranging from approximately ±1.17549e-38 to ±3.40282e+38, with a relative accuracy of around 1 in 10^6.
  • Double: Double has a wider range, covering approximately ±2.22507e-308 to ±1.79769e+308, and offers a higher relative accuracy of about 1 in 10^15.

Choosing Between Float and Double

When deciding whether to use float or double in your C programs, consider the following guidelines:

  • Precision Requirements: If your application requires higher precision, such as scientific computations or financial calculations, double is the preferred choice.
  • Storage Considerations: If memory optimization is crucial, and you can compromise on precision, float can be used to conserve memory.
  • Compatibility: Ensure compatibility with libraries or external systems that might expect a specific floating-point type.

Usage Scenarios

Let’s explore some common scenarios where the choice between float and double is relevant:

  • Graphics and Gaming: In graphics-intensive applications or gaming, double precision is often necessary to maintain accurate rendering and calculations.
  • Engineering and Scientific Calculations: Fields such as engineering or scientific research often require the higher precision of double for accurate results.
  • General Purpose Calculations: For general-purpose calculations where high precision is not critical, float can provide sufficient accuracy while conserving memory.


Understanding the difference between float and double is essential when working with floating-point numbers in C programming. Float offers a balance between precision and storage size, while double provides increased precision at the cost of more memory. By considering the precision requirements and storage considerations of your program, you can make an informed decision on whether to use float or double, ensuring accurate and efficient floating-point calculations in your C programs.