What is a number base (radix)?

A number base, or radix, is how many unique digits a numbering system uses before it carries over to the next place value. Decimal (base 10) uses digits 0-9; binary (base 2) uses 0-1; hexadecimal (base 16) uses 0-9 and a-f. This tool supports any base from 2 to 36, using letters a-z for digit values above 9.

Can this converter handle very large numbers?

Yes. It uses JavaScript's BigInt type internally instead of regular numbers, so there's no 32-bit or 53-bit precision loss — you can convert numbers hundreds of digits long exactly.

What happens if I enter a digit that's invalid for the source base?

The tool flags it immediately — for example, entering the digit 9 while the source base is set to 8 (octal only uses digits 0-7) shows an error explaining which character isn't valid for that base, instead of silently producing a wrong answer.

Base Converter

Convert a number between any base from 2 to 36.

This free online base converter (radix converter) takes a number in any base from 2 to 36 and shows it in binary, octal, decimal, hexadecimal, and a custom base of your choice — all at once. Built on arbitrary-precision integers, so there's no precision loss on large values. No signup required, runs entirely in your browser.

Source base

Custom:

Extra custom base

Shown alongside binary/octal/decimal/hex in the results.

Quick reference

255 (base 10): → FF (hex), 11111111 (binary)
FF (base 16): → 255 (decimal), 377 (octal)
1010 (base 2): → 10 (decimal), A (hex)

Value

How to use this base converter

A base converter (or radix converter) translates a number written in one numbering system into another. Enter a number, pick the base it's currently written in (2 to 36), and the result updates instantly — shown in binary, octal, decimal, hexadecimal, and any extra custom base you set, so you can cross-check the conversion however you think about it.

Under the hood, this tool parses the input digit-by-digit into a JavaScript BigInt using a multiply-accumulate loop (BigInt has no built-in arbitrary-radix string parser), then formats that BigInt back out using each target base. That means no floating-point precision loss — you can convert numbers hundreds of digits long and still get an exact result.

What number bases mean

Binary (base 2) — digits 0-1. The native representation used by computer hardware and low-level bit flags.
Octal (base 8) — digits 0-7. Used historically in Unix file permissions (e.g. chmod 755).
Decimal (base 10) — digits 0-9. The everyday counting system.
Hexadecimal (base 16) — digits 0-9 and a-f. Common in color codes, memory addresses, and byte-level debugging.
Base 36 — digits 0-9 and a-z, the highest base this tool supports, sometimes used to shorten IDs.

Converting by hand

To convert a number out of a given base, multiply each digit by the base raised to its place-value power and sum the results. For example, hex FF is 15×16 + 15 = 255 in decimal. To convert a decimal number into another base, repeatedly divide by the target base and read the remainders in reverse order.

Frequently asked questions

A number base, or radix, is how many unique digits a numbering system uses before it carries over to the next place value. This tool supports any base from 2 to 36, using letters a-z for digit values above 9.

Yes. It uses BigInt internally instead of regular numbers, so there's no precision loss even on numbers hundreds of digits long.

The tool flags it immediately — for example, entering the digit 9 while the source base is set to 8 shows an error explaining which character isn't valid for that base.

Prefix the input with a minus sign, e.g. -ff in base 16. The result in every base keeps the leading minus sign rather than using two's-complement representation.

No. Every conversion runs locally with JavaScript in your browser. Nothing is uploaded or stored on a server.