Binary to Decimal Converter
Convert binary numbers to decimal representation online. Free, fast, and runs entirely in your browser.
Input
Output
What Is Binary to Decimal Conversion?
Binary to decimal conversion transforms numbers from the base-2 (binary) numeral system into the base-10 (decimal) numeral system, which is a form of <a href="https://en.wikipedia.org/wiki/Positional_notation" target="_blank" rel="noopener">positional notation</a>. Each binary digit (bit) represents a power of 2. For example, the binary number 101010 equals 1x32 + 0x16 + 1x8 + 0x4 + 1x2 + 0x1 = 42 in decimal.
This conversion is essential when reading or debugging low-level computer data, network protocols, or hardware registers. Understanding <a href="https://www.tutorialspoint.com/computer_logical_organization/binary_arithmetic.htm" target="_blank" rel="noopener">binary arithmetic</a> is key to working with these systems. This tool converts binary strings to their decimal equivalents instantly, supporting multiple values and optional 0b prefixes.
How to Use This Tool
Enter Binary Numbers
Type or paste one binary number per line in the left editor. Numbers may optionally start with 0b. Click Sample to load examples, or Upload a text file.
View Decimal Output
The right panel updates automatically with the decimal value of each binary number. Invalid binary digits trigger an error message on that line.
Copy or Download
Click Copy to copy the decimal output to your clipboard, or Download to save it as a text file.
Conversion Examples
Here are some common binary to decimal conversions:
Binary Input
Decimal Output
Frequently Asked Questions
How does binary to decimal conversion work?
Each bit position represents a power of 2, starting from the rightmost bit (20 = 1). Multiply each bit by its positional value and sum the results. For example, 101010 = 1×32 + 0×16 + 1×8 + 0×4 + 1×2 + 0×1 = 42.
Does this support the 0b prefix?
Yes. The tool automatically strips a leading 0b or 0B prefix before conversion. In JavaScript, you can also use built-in Number methods for similar parsing.
Is my data sent to a server?
No. All processing happens locally in your browser. No data leaves your machine.
Does it support negative numbers?
Yes. A leading minus sign is preserved (e.g., -101010 becomes -42). For programmatic conversion, see the MDN Number reference.
Related Tools
Learn more: Britannica on numeral systems, Wolfram MathWorld Binary, and the MDN parseInt documentation.