Float vs Double

By | March 2, 2021
Float vs Double

In programming languages like C, C++, and Java we have two primitive data types float and double to represent floating points/real constant numbers. In simple words, floating points/real constant are those numbers that contain decimal points such as 5.000, 6.2123, etc. Both the real and decimal numbers considered under floating points numbers. And in this article, we will be discussing the difference between float and double.

Float vs Double

In C++ and Java, we have two in-built data types float and double to represent all floating points, but there is always confusion about which data type to choose as both are supposed to do the same work. In small-scale programming, we won’t be seeing any difference between float and double, but when we talk about data science or scientific computing even a single point can have a huge impact, there a programmer should have the complete knowledge of which data type should he/she use to represent a real number.


Here in this article, we have provided a head-to-head comparison between float and double data types and also mentioned when to choose which data type.

Before comparing both the data types let’s have a look at what is float and double?

What is a Float?

  • Float is a Single-precision floating-point format data type that is basically used to represent floating points number.
  • Float usually occupies 32 bits in computer memory with 4 bytes.
  • If we compare it to Integer data types, an integer can have a maximum value of 2,147,483,647, whereas a float can have a maximum value of 3.4028235 × 1038.
  • A float can provide 6 digits after the decimal point.

What is Double?

  • Double is an IEEE 754 64 bits Double-precision floating-point format data type which is also used to represent Floating points number.
  • IEEE 754 is a standard representation of floating points number in Computer. A double can occupy 8 bytes of space in computer memory and store 15 to 16 numbers after the decimal point.

As compare to float data type double show more preciseness and occupy more memory. The preciseness signifies the accuracy of the result.

Float vs Double: Head to Head Comparison

Parameter Double Float
Explanation Double-precision floating-point, use to represent floating points number Single-precision floating-point, use to represent floating points number
Memory 64-bits 32 bits
Size 8 bytes 4 bytes
Precisions More precision Less precision
Maximum Value or Range Double has more range than float 3.4028235 × 1038
Advantages It is more precise than float
  • Mostly all programming language have float data types
  • Manly libraries support it

Key Difference between Double and Float

The main reason behind using the floating-point real numbers is accuracy. Often in arithmetic operations, we come across such computational results where the digits after the decimal points are infinite and cannot be represented using any data types such as 2/3 (0.666666…).

For such infinite decimal digits, the float and double data types round up the decimal points after a certain digit. Although the rounding up of such real numbers do the task for us in most cases but think of scientific computation where a single decimal difference can have a huge impact on the overall result. In those cases, we require such data types that have more precision and store more decimal digits.

Although both double and float do not provide full accuracy and precision, but between them double comes with more precision over float. That’s the reason why C++ also provides long double data types for better floating point accuracy.

Here is a small table that represents the memory and range of double and float.

Type Memory (32/64 bits) Range
float 4 bytes 1.2E-38 to 3.4E+38
double 8 bytes 2.3E-308 to 1.7E+308
long double 16 bytes 3.4E-4932 to 1.1E+4932


In programming languages like C and C++, we get the option to declare a variable using float and double keyword, but in Java, it accepts the floating points number as a float data type. In Java, we have to explicitly typecast the decimal number using the ‘f’ suffix else the JVM treats the decimal number as a double.

float x=2.2234;
double y = 2.34244;

float x= 2.343f;
double y = 2.3435;

When to use Float?

We generally use a float with a low-scale program where point accuracy does not matter that much. As it has less size and occupies only 32 bits of memory, which makes it very fast to compute. If you want to make a program as minimum as possible then you should use float data type for floating points number.

Where to use double?

When you are writing code for high-end computers where RAM shortage and battery drainage are not such an issue there you should use double data type.

Double provides more range and precision as compared to float, so if accuracy is your main concern then you should use double data type.


Float and Double are the two most confusing data types of C, C++, and Java. In most cases, it does not even matter whether you use the float or double. From the memory perspective- these days we do not have to worry about the size of a data variable, because we have high processing CPUs with multiple cores. On the other hand, precision can be the foremost reason to shift the data type from float to double. In other programming languages like JavaScript, PHP, and Python we do not have dedicated data types for the floating-point numbers there we only get a float.

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