Tools / Number Base Converter
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal — instantly, right in your browser.
Everything runs locally in your browser.
// About this tool
Number Base Converter
This converter translates a number between the four bases you meet most in computing: binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). Type a number, choose the base it's in, and see it converted to every other base at once.
Each base is just a different way of writing the same quantity. Binary uses only 0 and 1, octal uses 0–7, decimal uses 0–9, and hex uses 0–9 plus a–f.
Everything runs locally in your browser. There is no server, so nothing you enter is transmitted, and the tool works fully offline.
// When to use it
Read a hex color or memory address
Convert a hex value like 2a to decimal (42) or binary (101010) to understand the underlying number.
Work with binary flags or masks
Convert a decimal permission value to binary to see which bits are set at a glance.
Check your arithmetic
Quickly confirm a conversion you're doing by hand against the tool's instant result.
// Questions
Is my number sent to a server?
No. All conversion happens locally in your browser. Nothing is uploaded, and the tool works offline.
What bases are supported?
Binary (2), octal (8), decimal (10), and hexadecimal (16).
Does it handle negative numbers?
Yes. A leading minus sign is preserved through all conversions.
Why does hex use letters?
Base 16 needs sixteen symbols, so it uses 0–9 for the first ten and a–f for the last six (10 through 15 in decimal).
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