What Is a Double Precision Float Data Type?


Heather Bennett

Double precision float data type, also known as double, is a fundamental data type in programming that is used to store decimal numbers with high precision. It is commonly used in scientific and mathematical calculations where accuracy is of utmost importance. In this article, we will explore the double precision float data type in detail and understand its significance.

What is Double Precision Float Data Type?

A double precision float data type is a numeric data type that represents real numbers with extended precision. It occupies 8 bytes (64 bits) of memory and can store values ranging from approximately ±2.23 × 10-308 to ±1.79 × 10308. The double precision float provides significantly higher precision compared to the single precision float data type.

Why Use Double Precision Float Data Type?

The primary reason for using the double precision float data type is its ability to provide greater accuracy in calculations involving decimal numbers. Unlike other numeric types like integers or single precision floats, doubles can represent fractions and very large or small numbers more precisely.

Scientific computations, financial calculations, and simulations often require high levels of accuracy. A slight discrepancy in these calculations can lead to significant errors in the final results. By using the double precision float data type, programmers can ensure more accurate and reliable outcomes.

How to Declare a Double Precision Float?

In most programming languages, you can declare a variable of double precision float using specific syntax or keywords. Here’s an example in JavaScript:

let pi = 3.14159;
let radius = 5.0;
let circumference = 2 * pi * radius;

In this example, we declare the variables “pi” and “radius” as double precision floats. We then use these variables to calculate the circumference of a circle.

Notes on Double Precision Float Data Type

Here are a few important points to keep in mind while working with double precision float data type:

  • Precision: Double precision floats provide approximately 15 decimal digits of precision.
  • Memory Usage: Since double precision floats occupy 8 bytes of memory, they consume more memory compared to other numeric data types.
  • Performance: Performing calculations with double precision floats can be relatively slower than using other numeric types due to the increased precision and memory requirements.


In conclusion, the double precision float data type is a valuable tool for programmers working with decimal numbers that require high accuracy. Its extended precision and ability to represent large or small values make it an essential part of scientific and mathematical calculations.

However, it’s important to consider its memory usage and potential performance impact when working with large datasets or computationally intensive tasks.

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