Conversion is live: type a number, pick the base it is written in, and the binary, octal, decimal and hexadecimal forms appear instantly, each with a copy button. A custom base row covers every other base from 2 to 36, from ternary to hexatrigesimal. Digits above 9 use the letters A to Z, and results are grouped for readability - spaces in binary and hex, commas in decimal - with the separators stripped automatically when you paste a grouped number back in.
Private browser utility / Developer
Number Base Converter
Runs entirely in your browser - no upload, no sign-up.
Number base converter
Number and base
Enter a number and pick the base it is written in - the conversions appear as you type.
Common bases
Binary (2)
Octal (8)
Decimal (10)
Hexadecimal (16)
Custom base
Base 36 (Hexatrigesimal)
What is a number base converter?
A number base converter rewrites a number from one base (or radix) into another. This tool converts whole numbers between binary (base 2), octal (8), decimal (10) and hexadecimal (16) as you type, plus any custom base from 2 to 36. It uses BigInt, so even 100-digit numbers convert exactly, and everything runs in your browser.
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How to use
- 01Enter your number
Type the number you want to convert. Grouping separators like spaces or commas are fine - they are stripped automatically.
- 02Pick its base
Choose the base your input is written in, from 2 (binary) to 36. The default is decimal (base 10).
- 03Read the results
Binary, octal, decimal and hexadecimal appear instantly, each with a copy button. Use the custom base row for any other base from 2 to 36.
- 04Copy what you need
Press Copy on any result to put it on your clipboard. Invalid digits for the chosen base show a clear error instead of a wrong answer.
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Who it's for
- Developers translating between binary, hex and decimal when debugging memory dumps, bitmasks or color values.
- Students checking their homework on base conversion - binary to decimal, hex to binary, octal to anything.
- Network and systems engineers converting IP octets, subnet masks and MAC addresses between decimal and hex.
- Anyone working with big integers - IDs, hashes or timestamps - who needs an exact conversion without floating-point rounding.
FAQ
Is this number base converter free?
Yes - it's completely free with no sign-up. All conversion happens locally in your browser, so there are no limits on the size of the numbers you convert.
Is my number uploaded anywhere?
No. The conversion runs entirely on your device and nothing is sent to a server, so it is safe for private IDs, keys and configuration values.
How do I convert binary to decimal?
Type the binary number (digits 0 and 1), set the From base dropdown to 2, and read the Decimal row. The conversion updates as you type, so you can also paste a long binary string and watch it resolve.
What bases are supported?
Any whole-number base from 2 to 36. Bases 2, 8, 10 and 16 are shown together for convenience, and the custom base row covers everything else, including ternary (3), duodecimal (12) and hexatrigesimal (36).
What do the letters A to F (and beyond) mean?
Bases above 10 need symbols for digits past 9. The tool uses A for 10, B for 11, and so on up to Z for 35, so hexadecimal uses A to F and base 36 uses the full alphabet. Input is case-insensitive: a and A are the same digit.
Why does my binary result have spaces in it?
Binary and hex results are grouped in blocks of four digits and decimal in blocks of three, purely for readability. The separators are stripped automatically when you paste a grouped number back into the input, so the round trip is exact.
Can it convert very large numbers?
Yes. Conversion uses BigInt, so there is no 2^53 limit and no rounding. A 100-digit decimal number converts to binary exactly, which is useful for long IDs, hashes and 64-bit timestamps.
Does it handle negative numbers or two's complement?
Negative numbers are supported with a leading minus sign, and the tool converts the magnitude: -255 in decimal is -FF in hex. It does not apply two's complement, so -1 is -1 in every base, not a string of F's.