Number Base Converter — Binary, Octal, Hex, Decimal Free
Convert numbers between binary, octal, decimal, and hexadecimal. All four values update simultaneously as you type. Runs in your browser — no upload, no account, no logs.
How to use this tool
- Enter a number and select its current base (binary, octal, decimal, or hex).
- See the instant conversions across all bases.
- Copy the value in the target base.
About Number Base Converter
This converter translates a whole number between the four bases programmers reach for most: binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). You pick which base your input is written in using the row of buttons, type the value, and all four representations appear together and update live with every keystroke. Each result has its own copy button so you can grab the binary, octal, decimal, or hex form without retyping it.
Input is validated against the base you selected, so a digit that cannot exist in that base, such as the letter G in hex or the digit 8 in octal, produces a clear message naming the expected base rather than a silent wrong answer. Common prefixes are accommodated: a leading 0x on hex input and a leading 0b on binary input are stripped automatically, so you can paste values straight from source code. Hexadecimal output is shown in uppercase for readability, and the conversion is case insensitive on input.
Because the math runs through JavaScript's native number handling, the tool enforces the safe integer ceiling of 2 to the 53rd power minus one. Any value that would exceed that limit is rejected with an explanation, which prevents the silent precision loss that would otherwise corrupt very large numbers. This keeps every shown conversion exact rather than approximate. All processing happens in your browser, so the numbers you enter are never transmitted anywhere.
It is a quick aid when reading memory addresses, RGB color components, file permission bits, bitmask flags, or network values, and when you simply need to confirm what a hex literal means in plain decimal. For everyday programming numbers it removes the mental arithmetic and the risk of an off-by-one slip in manual base conversion.
Frequently Asked Questions
- Which number bases can it convert between?
- Binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). You select the base of your input, and the tool shows the value in all four bases at once, each with its own copy button.
- Can I paste values with 0x or 0b prefixes?
- Yes. A leading 0x on hexadecimal input and a leading 0b on binary input are detected and removed automatically, so you can paste literals copied directly from code without editing them first.
- What is the largest number it can handle?
- Up to 2 to the 53rd power minus one, which is JavaScript's largest safely representable integer. Values above that are rejected with a message, because converting them would risk silent rounding and produce inexact results.
- Why am I getting a not a valid number error?
- The input contains a character that cannot appear in the base you selected, for example an 8 or 9 in octal mode, or a letter beyond F in hexadecimal mode. Check that the digits match the chosen base, and the conversion will proceed.
- Does hexadecimal output use uppercase or lowercase?
- Output is shown in uppercase, such as FF rather than ff. Input is accepted in either case, so you do not have to worry about how you typed it.
- Does it support negative numbers or fractions?
- No. The converter works with non-negative whole numbers. There is no support for negative values, decimal points, or two's complement representations, so it is focused on the unsigned integer conversions that come up most often in programming.
- Does it handle leading zeros?
- Yes. Leading zeros in the input are accepted and the value is interpreted normally; the outputs are shown without unnecessary padding. If you need a fixed bit width, pad the binary result yourself after copying it.
- Are the numbers I enter sent anywhere?
- No. Every conversion is computed locally in your browser, so nothing you type is uploaded.
Embed this tool on your site
Free. One line of HTML — the tool runs in your visitor's browser, no data sent to anyone.
<iframe src="https://brevio.pro/embed/number-base-converter" width="100%" height="600" loading="lazy" style="border:1px solid #e5e5e5;border-radius:8px" title="Number Base Converter — brevio"></iframe> <p style="font:12px/1.4 sans-serif"><a href="https://brevio.pro/tools/number-base-converter">Number Base Converter</a> by <a href="https://brevio.pro">brevio</a></p>