Number Base Converter
Convert a number between binary (2), octal (8), decimal (10) and hexadecimal (16) — or any base from 2 to 36. Everything runs live in your browser — your data is never sent anywhere and nothing is stored.
How to use the number base converter
- Type a number into the box and pick the base it is currently written in (From base).
- The binary, octal, decimal and hexadecimal equivalents update live as you type.
- Set the Custom base field (2–36) to convert to any other radix, and use Copy on any row.
Valid digits depend on the base: base 2 allows only 0–1, base 8 allows 0–7,
base 16 allows 0–9 and A–F, and bases up to 36 use 0–9 then A–Z.
Large integers are handled with BigInt so no precision is lost.
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Frequently asked questions
What is a number base?
A number base (or radix) is how many distinct digits a numbering system uses before it rolls over to the next place value. Decimal (base 10) uses digits 0–9; binary (base 2) uses only 0 and 1; octal (base 8) uses 0–7; and hexadecimal (base 16) uses 0–9 plus A–F. The same quantity can be written in any base — only the notation changes, not the value.
How does hexadecimal work?
Hexadecimal is base 16, so each digit holds a value from 0 to 15. The values 10–15 are written as the letters A–F (A=10, B=11, … F=15). It is popular in computing because one hex digit maps exactly to four binary bits, so a byte is just two hex digits — for example 255 in decimal is FF in hex and 11111111 in binary.
How large a number can it convert?
Very large ones. The converter uses JavaScript BigInt arithmetic, which supports arbitrarily large whole numbers limited only by your device memory — so it will not lose precision the way ordinary floating-point numbers do past about 9 quadrillion. Note that it works with whole integers, not fractions or decimals.
Is my input stored anywhere?
No. The conversion runs entirely in your browser — nothing is uploaded to a server and nothing is stored. You can use it offline once the page has loaded.