Number base converter
Convert a whole number between binary, octal, decimal, hexadecimal and any base from 2 to 36 — with arbitrary precision (BigInt), live as you type. Fully offline.
Open Number base converter →What is the number base converter?
A number base converter that turns a whole number between binary, octal, decimal, hexadecimal and any base from 2 to 36, live as you type. It uses arbitrary-precision arithmetic (BigInt), so very large numbers stay exact, and it runs entirely in your browser, fully offline.
How to use Number base converter
- Enter your number — Type the whole number you want to convert into the Number field. Underscores and commas are ignored, so you can group digits for readability.
- Choose the input base — Set "From base" to tell the tool how to read your number — binary, octal, decimal or hexadecimal.
- Read the conversions — The binary, octal, decimal and hexadecimal results appear instantly and update as you type.
- Try a custom base — Set the "Custom base" field to any value from 2 to 36 to see the same number in that base, using letters a–z for digits above 9.
Frequently asked questions
How large a number can it handle?
Arbitrarily large whole numbers. It uses BigInt arithmetic, so results stay exact even for numbers far beyond the usual integer limits.
Which bases are supported?
Binary, octal, decimal and hexadecimal are shown directly, plus any custom base from 2 to 36. Digits above 9 are written as the letters a–z.
Can it convert negative numbers?
Yes. Prefix the value with a minus sign and the converted results keep the sign across every base.
Why am I seeing a digit error?
A character in your number isn't valid for the chosen input base — for example the letter F in a binary value. The message names the offending digit and the base so you can correct it.
Does it handle decimal points or fractions?
No. This converter works with whole numbers only; fractional parts and decimal points aren't supported.
Tips
- Group long inputs with underscores or commas — they're ignored, so 1_000_000 reads fine.
- Hexadecimal output is shown in uppercase, which is the common convention for hex.
- Set the custom base to 32 or 36 for compact encodings of large numbers.
- Switch "From base" to read the same digits as a different base without retyping.