Both real and decimal numbers are floatingpoint numbers, and in this article, we will be discussing the difference between float and double, i.e., float vs double. In programming languages like C, C++, and Java, we have two primitive data types, float and double, to represent floatingpoint numbers and real constant numbers.
In simple words, floatingpoint numbers or real constants are those numbers that contain decimal points, such as 5.000 and 6.2123.
Float vs Double
In C++ and Java , we have two inbuilt data types, float and double, to represent all floatingpoint numbers, but there is always confusion about which data type to choose as both are supposed to do the same work.
In smallscale 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. Here, a programmer should have knowledge of which data type should be used to represent a real number.
Here in this article, we have provided a headtohead comparison between float and double data types and also mentioned when to choose each of them. Before comparing the two data types, let's have a brief look at each of them.
What is a Float?
Float is a singleprecision floatingpoint format data type that is basically used to represent floatingpoint numbers. It usually occupies 32 bits in the computer memory with 4 bytes. An integer can have a maximum value of 2,147,483,647, whereas a float can have a maximum value of 3.4028235 × 10 ^{ 38 } . Also, a float can provide six digits after the decimal point.
What is a Double?
Double is an IEEE 754 64 bits doubleprecision floatingpoint format data type, which is also used to represent floatingpoint numbers. IEEE 754 is a standard representation of floatingpoint numbers in a computer.
A double data type can occupy 8 bytes of space in the computer memory and stores 15 to 16 numbers after the decimal point. Compared to the float data type, double shows more precision and occupies more memory. The precision signifies the accuracy of the result.
Float vs Double: A HeadtoHead Comparison
Parameter  Double  Float 
Explanation  It is a doubleprecision floatingpoint data type. It is used to represent floatingpoint numbers.  Float is a singleprecision floatingpoint data type that is used to represent floatingpoint numbers. 
Memory  64bit  32bit 
Size  8 bytes  4 bytes 
Precision  Double offers more precision.  It offers less precision. 
Maximum Value or Range  Double has more range than float.  3.4028235 × 10^(38) 
Advantages  It is more precise than float. 

Key Difference Between Double and Float
The main reason behind using floatingpoint 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 type.
For example, 2/3 (which goes on endlessly to 0.666666...). For such infinite decimal digits, 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, think of scientific computation, where a single decimal difference can have a huge impact on the overall result. In those cases, we require data types that have more precision and store more decimal digits.
Both double and float do not provide full accuracy and precision, but between the two, double comes out on top with more precision. That's the reason why C++ also provides the long double data type for better accuracy of floatingpoint numbers. The following table represents the memory and range of double and float.
Type  Memory (32/64 bits)  Range 
float  4 bytes  1.2E38 to 3.4E+38 
double  8 bytes  2.3E308 to 1.7E+308 
long double  16 bytes  3.4E4932 to 1.1E+4932 
In programming languages like C and C++, we get the option to declare a variable using either the float or double keyword, but in Java, it accepts floatingpoint numbers 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.
//c++ float x=2.2234; double y = 2.34244; //java float x= 2.343f; double y = 2.3435;
When to Use Float?
We generally use the float data type with a lowscale program where point accuracy does not matter that much. 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 small as possible, then you should use float data type for floatingpoint numbers.
When to Use Double?
When you are writing code for highend computers where RAM consumption and battery drainage are not the major issues, you should use the double data type. Double provides more range and precision as compared to float. Therefore, if accuracy is your main concern, then you should use the double data type.
Conclusion
Float and double are the two most confusing data types of programming languages like C, C++, Java. In most cases, it does not matter whether you use float or double. These days, we do not have to worry about the size of a data variable because we have high processing CPUs with multiple cores nowadays.
On the other hand, precision can be the major 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 floatingpoint numbers. There, we only get the float data type.
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