Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal — instantly in your browser.
Type a decimal number above to see all conversions.
How to use it
- 1Type a number into any of the four fields — Binary, Octal, Decimal, or Hexadecimal.
- 2All other fields update instantly to show the same value in their respective base.
- 3The Bit length row below shows how many bits are needed to represent the number in binary.
- 4Prefixes (0b, 0o, 0x) are stripped automatically, so you can paste a prefixed value and it will still parse correctly.
Common use cases
- Decode a hexadecimal color or memory address into its decimal equivalent for debugging.
- Convert a decimal permission mask into binary or octal to understand Unix file permissions (e.g. 755).
- Cross-check a binary value you're hand-writing in an embedded systems project against its hex equivalent.
- Teach or learn binary arithmetic — watch how incrementing in decimal affects the binary representation.
- Convert a hex API response field into decimal for human-readable comparison.
Frequently asked questions
- Does it handle hexadecimal letters?
- Yes. The hex field accepts both uppercase (A–F) and lowercase (a–f). The output is always shown in uppercase for readability.
- What's the largest number it can convert?
- JavaScript's safe integer range — up to 2^53 − 1 (9,007,199,254,740,991 in decimal). For most practical purposes this is more than enough; very large cryptographic values would require a big-integer library.
- Can I enter a negative number?
- No — negative numbers and two's-complement representation are not supported. The tool converts non-negative integers only.
- Why does the bit-length change as the number grows?
- Bit length is the number of binary digits needed to represent the value — i.e. the length of the binary string without leading zeros. 1 needs 1 bit; 4 needs 3 bits; 255 needs 8 bits. It tells you the minimum word size to store that value.
- Is anything sent to a server?
- No. Conversion runs in your browser using JavaScript's built-in parseInt and Number.prototype.toString with a radix. Nothing leaves your device.