In1.

Number base converter

Enter a number in binary, octal, decimal or hexadecimal and instantly see it in all four bases at once. Each result is validated and ready to copy, with everything computed in your browser.

Loading tool…
All Web tools

How to use Number Base Converter

  1. 1

    Choose the input base

    Tap binary, octal, decimal or hexadecimal to set what you're starting from.

  2. 2

    Enter your number

    Type the value in the selected base.

  3. 3

    Read all four bases

    The equivalent in binary, octal, decimal and hex appears instantly.

  4. 4

    Copy a result

    Copy any of the converted values with one click.

Convert between all four common bases at once

Numbers can be written in different bases, and converting between them by hand is fiddly and error-prone. Decimal, base ten, is what people use every day. Binary, base two, is the language of computers, built from only ones and zeros. Hexadecimal, base sixteen, is a compact way to write binary that programmers use constantly for colors, memory addresses, byte values and more. Octal, base eight, still shows up in places like file permissions. This converter takes a number in any one of these bases and shows you the equivalent in all four simultaneously, so you never have to do the conversion in your head or chain together several steps. Enter a hex color component and read its decimal value; type a decimal number and see its binary form; paste a binary string and get the hex. Because all four results appear together and update as you type, you get the full picture of a value at once, which is far quicker than converting one pair at a time.

Pick your input base and type away

To convert a number correctly, the tool needs to know what base you are starting from, because the same digits can mean different things in different bases — '10' is ten in decimal but two in binary, eight in octal and sixteen in hex. In1 lets you choose the input base with a single tap, and then interprets whatever you type accordingly. As soon as you enter a value, the conversions to the other three bases appear instantly. This makes the tool comfortable for quick one-off lookups and for working through a series of values: set the base once and keep typing. The decimal result is always shown so you can anchor an unfamiliar binary or hex value to a number you intuitively understand, and the hexadecimal output is shown in a clean, consistent form. There is no submit button and no mode-switching beyond choosing the base — you select where you are starting from and the answers follow immediately.

Validation that catches bad input

One of the easiest mistakes when working with bases is entering a digit that does not belong: a '2' in a binary number, an '8' in an octal one, or a stray letter in a decimal value. A naive converter might silently produce a wrong answer, which is worse than no answer because you might trust it. In1 validates your input against the base you have selected and tells you clearly when the value is not legal for that base, rather than guessing or returning garbage. It also guards against numbers too large to convert reliably, so you are warned instead of getting a silently truncated or inaccurate result. This validation turns the converter into something you can actually rely on: when it shows you a set of results, you know the input was well-formed and the conversions are correct. Catching the error at the moment you type it, with a plain message explaining the problem, saves you from chasing a bug that started as a single mistyped digit.

Private, instant and free

Base conversion is pure arithmetic, and there is no reason it should involve a server. In1 computes every conversion locally in your browser using the platform's own number handling, so whatever values you are working with stay entirely on your device. Nothing is uploaded, nothing is stored and there is no account or sign-up. The results appear the instant you type, with no network request, so the converter is immediate and works exactly the same offline as online — handy when you are deep in a project without a reliable connection. Each result sits next to a copy button, so moving a converted value into your code, a config file, a calculator or a document takes a single click. There are no limits and no clutter. It is a small, focused utility, but base conversion is something developers and students reach for surprisingly often, and having it give you all four bases at once, validated and instant, is exactly what that recurring need calls for.

Who uses a number base converter?

It is a constant companion for anyone close to how computers represent numbers. Programmers convert between decimal and hexadecimal for color codes, memory addresses, bitmasks, byte values and status codes, and read binary to reason about individual bits. Embedded and low-level developers live in hex and binary and convert to decimal to sanity-check values. Students learning computer science practice converting between bases as a core skill and use the tool to check their work. Network engineers convert values while working with addresses and subnet masks. System administrators decode octal file permissions. Electronics and hardware hobbyists translate register values between bases. Anyone working with hashes, encodings or low-level data formats occasionally needs to flip a number from one base to another. For all of them, a converter that takes any base as input and shows all four outputs at once — validated, instant and private — replaces both mental arithmetic and the risk of a quietly wrong conversion with a quick, trustworthy lookup.

Get more from In1

Higher limits, batch processing and an API are on the way. Want early access?

Frequently asked questions

More Web tools