Base Converter

Decimal into binary, octal and hexadecimal at once.

Decimal into binary, octal and hexadecimal at once. One number shown in every common base at once.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Value in decimal

Binary

11111111

8 bits

Decimal255

Binary11111111

Octal377

HexadecimalFF

Bits required8

Every base writes the same quantity differently — 255 is 11111111 in binary and FF in hex, and none is more correct than the others. Hexadecimal earns its place in computing because one hex digit is exactly four binary digits, so conversion between them needs no arithmetic at all.

How the Base Converter works

One number shown in every common base at once. None of them is more correct than the others. They are the same quantity written differently, and the choice is only ever about which is easiest to read for the task in hand.

Also known as: number base converter · convert number base · radix converter · decimal to binary octal hex

Where to go next

The Base Converter question rarely arrives on its own. These are the ones that usually come with it:

Binary Calculator — Binary to decimal, hex and octal, with validation that works.
Hex Calculator — Hexadecimal to decimal, binary and octal.
Octal Calculator — Octal to decimal, binary and hexadecimal.
Percentage Calculator — Every common percentage question in one place.

Sources

NIST Digital Library of Mathematical Functions

Frequently asked questions

What is a number base?

How many digits the system uses before it carries. Decimal has ten, binary two, octal eight, hexadecimal sixteen.

How do I convert between bases?

Through decimal, or directly when the bases are related. Binary to hex needs no arithmetic at all, since four binary digits make one hex digit.

How many bits does my number need?

The length of its binary form. This page shows it, which is what determines whether a value fits in a byte, a short or an int.

Why do computers use binary?

Because a circuit is reliably either on or off, and two states are far easier to distinguish than ten. Everything else is built on that.

Put this calculator on your own site

Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.

The one-line version

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