UsefulTab
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal.
Enter a number to convert between bases
Enter a whole number in binary, octal, decimal, hex, or your own base to see it shown in every base at once, with copy-to-clipboard buttons.
Convert numbers between bases, locally
A number base — or radix — is how many distinct digits a numbering system uses. Decimal (base 10) uses 0–9, binary (base 2) uses 0 and 1, octal (base 8) uses 0–7, and hexadecimal (base 16) uses 0–9 plus A–F. The same value can be written in any of them. Type a whole number into any field — binary, octal, decimal, or hex — and the other three update instantly. A custom-base row lets you read or write the value in any radix from 2 to 36, using letters beyond 9 exactly as hexadecimal does. Invalid digits for the chosen base are rejected so you always see a clean conversion. Everything runs in your browser with the native BigInt type, so very large integers convert without losing precision, and nothing is uploaded.
Common questions
Which bases can I convert between?
The four common programming bases each have their own field: binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). The custom-base row accepts any radix from 2 to 36 — bases above 10 use the letters A–Z for the extra digits, just like hexadecimal uses A–F.
Does it handle very large numbers?
Yes. The converter uses JavaScript's native BigInt, so it works with arbitrarily large whole numbers without the rounding errors that ordinary floating-point numbers introduce past about 9 quadrillion. There is no practical digit limit.
Can I convert negative numbers or decimals?
Negative whole numbers are supported — just include a leading minus sign. Fractional values (like 3.14) are not, because this tool converts integers between bases; a binary or hex representation of a fraction depends on a chosen precision and format that vary by use.
What happens if I type an invalid digit?
Each field only accepts digits that are valid for its base — for example the binary field rejects anything other than 0 and 1, and the hex field accepts 0–9 and A–F. If a value is not valid for its base the tool leaves the other fields unchanged and tells you in the status line.
Is my data sent anywhere?
No. The conversion is pure arithmetic running in your browser tab. No number you type is uploaded to a server — it is fully client-side and private.