Number Base Converter

Convert numbers between binary, octal, decimal, hexadecimal, and any base from 2 to 36. Instant, client-side.

Runs in your browser — nothing uploaded

Value

Input base

Binary (base 2)

11111111

Octal (base 8)

377

Decimal (base 10)

255

Hex (base 16)

Custom base (36)

Try:

Use this free number base converter to translate between binary, octal, decimal, hexadecimal, and any base from 2 to 36 instantly. Built on BigInt so even very large numbers convert without precision loss — useful for hashes, encoded IDs, and low-level debugging.

Private by design — your data never leaves your device

How to use it

No account, no upload — it all happens on your device.

Type a number into the input box and pick its base.

Binary, octal, decimal, and hex versions appear instantly.

Drag the custom-base slider for any radix from 2 to 36.

Copy any value with one click.

The common bases at a glance

Where you actually meet each base in real code.

Base	Where you see it	255 looks like
2 (binary)	Bit-level masks, flags, microcontrollers	11111111
8 (octal)	Unix file permissions, legacy C constants	377
10 (decimal)	Human numbers, prices, counts	255
16 (hex)	Colors, byte values, hashes, memory dumps	ff
32	Crockford Base32 — IDs, ULIDs	7v
36	Compact short IDs, license plate codes	73

Why bases above 10 use letters

The notation is older than it looks.

A number written in base b needs b distinct digit symbols. We have ten Arabic digits (0–9) for free. For larger bases, the convention is to keep counting with letters: a = 10, b = 11, …, f = 15 (the full hex alphabet), continuing through z = 35 for base 36.

This is why 0xff is 255 and not 0 x f f. The 0xis just a marker telling a parser “the following digits are hexadecimal”. Most languages use it; this tool accepts (and strips) it for convenience.

Useful conversions to keep in your head

1 byte = 8 bits = 0–255 (decimal) = 00–ff (hex). Memorise this and most low-level work gets easier.
1 kilobyte = 1024 bytes = 2¹⁰. Powers of two appear everywhere in systems work.
1 MiB = 1024 KiB. The capital M and the i matter — 1 MB technically means 1,000,000 bytes (SI), while 1 MiB means 1,048,576 (binary). Storage vendors use MB to sound bigger.
RGB colors are two hex digits per channel: red, green, blue. #ff8800 = (255, 136, 0).
Unix permissions are three octal digits: owner, group, other. Each digit packs read (4), write (2), execute (1).

Frequently asked

Which bases are supported?

Any base from 2 (binary) to 36. Bases 2, 8, 10, and 16 are shown side by side; a slider lets you convert to any other base, with letters a–z used for digits beyond 9.

Can it handle very large numbers?

Yes. The tool uses JavaScript BigInt under the hood, so there's no precision limit — convert 256-bit hex hashes, large keys, or arbitrarily long binary strings without rounding.

Are 0x, 0b, 0o prefixes supported?

Yes. Paste with or without the prefix and the parser strips it. Underscores and whitespace inside the number are ignored too, so deadbeef and DE_AD_BE_EF parse identically.