Number Base Converter
Convert integers between binary, octal, decimal, hexadecimal, and any base from 2 to 36 — updates instantly as you type.
| Binary | |
|---|---|
| Octal | |
| Decimal | |
| Hexadecimal |
How to use this tool
Pick the base your number is currently in, type the value, and every other base (binary, octal, decimal, hex, and an optional custom base) updates instantly.
About this tool
Conversion uses JavaScript's built-in parseInt(value, base) and Number.prototype.toString(base), which correctly handle any base from 2 to 36 (using digits 0-9 and letters A-Z for bases above 10).
100% client-side. Supports integers up to Number.MAX_SAFE_INTEGER (9,007,199,254,740,991) exactly.
Frequently asked questions
What's the largest number this tool can convert?
Up to Number.MAX_SAFE_INTEGER (9,007,199,254,740,991), the largest integer JavaScript can represent exactly. Larger values may lose precision.
Does this support negative numbers?
Yes — enter a leading minus sign in the input for the source base, and it carries through to all target bases.
Why does the input show an error for certain digits?
Each base only allows specific digits — binary allows just 0 and 1, octal allows 0-7, decimal allows 0-9, and hexadecimal allows 0-9 and A-F. Entering a digit outside the valid range for the selected base (like an '8' in binary) triggers a validation error.