What Is the Precision of Double Data Type?


Angela Bailey

What Is the Precision of Double Data Type?

When working with numbers in programming, it’s important to understand the precision of different data types. One commonly used data type is the double, which is used to store floating-point numbers with a higher degree of precision compared to the float data type.

Understanding the Double Data Type

The double data type in programming languages such as Java and C++ is a 64-bit floating-point number. It can store both integer and decimal values with a higher range and precision compared to other numeric data types.

The double data type follows the IEEE 754 standard for representing floating-point numbers. This standard defines how the bits are allocated for the sign, exponent, and fraction parts of the number. The sign bit determines whether the number is positive or negative, while the exponent and fraction bits determine the magnitude and precision of the number.

Precision of Double Data Type

The precision of a double data type depends on its size (64 bits) and how it allocates those bits to represent numbers. In general, a double can represent about 15 to 17 significant decimal digits.

It’s important to note that although a double can represent a large range of values, it may not always be able to represent every decimal value with perfect accuracy. This is because floating-point numbers are stored in binary format, which can introduce rounding errors when converting between binary and decimal representations.

Rounding Errors

Rounding errors occur when a decimal value cannot be represented exactly using binary fractions. For example, consider the decimal value 0.1.

This value cannot be represented accurately in binary format due to its recurring fractional part (0.00011001100110011..). As a result, when you assign 0.1 to a double variable and print its value, you may see a slight rounding error.

These rounding errors are usually small and insignificant for most applications. However, they can accumulate over multiple calculations, leading to larger discrepancies in the final results.

When to Use Double Data Type

The double data type is typically used when higher precision is required, such as in scientific calculations, financial applications, or any scenario where accuracy is crucial. It provides enough precision for most practical purposes while still maintaining a good range of representable values.

  • Scientific Calculations: The double data type is commonly used in scientific calculations that involve complex mathematical functions and operations.
  • Financial Applications: Financial applications dealing with large numbers or precise calculations often rely on the double data type.
  • 3D Graphics and Simulations: The double data type can be useful in computer graphics and simulations that require accurate representation of coordinates or physical properties.


The double data type provides a higher degree of precision compared to other numeric data types. It allows programmers to work with floating-point numbers with a larger range and accuracy.

However, it’s important to be aware of the potential for rounding errors when using double values in calculations. By understanding the precision limitations of the double data type, you can make informed decisions about when and how to use it in your programs.

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