Number Base Converter

How to Use the Number Base Converter

Enter an integer into any of the binary, octal, decimal or hexadecimal fields, and the rest convert instantly. Use the button beside each field to copy that value.

• Start from any field: whichever field you edit becomes the source, and the other three fields plus the custom-base field update live.
• Hex is case-insensitive: FF and ff are treated as the same value.
• Custom base (2–36): choose a base in the dropdown and type a value on the left to convert both ways. Digits use 0-9 and a-z.
• Big integers supported: conversions run on BigInt, so huge integers beyond 64 bits convert without rounding errors.

For example, type 255 in the decimal field and it becomes 11111111 in binary, 377 in octal and FF in hex on the spot. Paste a prefixed value copied from code — such as 0xFF, 0b1010 or 0o755 — into any field and the base is detected automatically.

Where This Comes in Handy

• Checking color codes (#ff8800) or bitmasks between hex and decimal
• Reading network subnets or permissions (octal, like chmod 755)
• Translating memory addresses or register values between binary and hex
• Working with unusual bases such as base 32 or base 36 in puzzles and assignments

Binary, octal and hexadecimal reference table

The values that come up most in programming and bit manipulation, including the powers of two that sit on type boundaries (255/256, 1023/1024, 65535).

255 is the largest unsigned value in one byte (eight binary 1s) and 65535 the largest in two. The tool above converts between any bases from 2 to 36 and handles large integers.

Frequently Asked Questions