Number Base Converter
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Convert any number between binary, octal, decimal and hexadecimal at the same time. Type a value in the base you have, and the other three bases update instantly — with the binary grouped into 4-bit chunks for easy reading. Everything runs in your browser; nothing is uploaded.
How to use
- Pick the base your number is written in (BIN, OCT, DEC or HEX).
- Type or paste the number — prefixes like 0x, 0b, 0o and underscores are accepted.
- Read the value in all four bases and copy any of them with one click.
How number bases relate
Every whole number has one value but many written forms. Decimal (base 10) is what we use day to day. Binary (base 2) is how computers store data, hexadecimal (base 16) is a compact way to write bytes and colors, and octal (base 8) shows up in file permissions. The example below shows the single value 255 written in all four bases.
Features
All four bases at once
Binary, octal, decimal and hexadecimal are shown together and stay in sync as you type.
Grouped bits
The binary result is split into 4-bit groups so long bit patterns are easy to scan.
Very large numbers
Built on BigInt, so it handles values far beyond 64 bits without losing precision.
Prefix friendly
Common prefixes (0x, 0b, 0o) and underscore separators are accepted in the input.
One-click copy
Copy any representation straight to your clipboard for use in code or notes.
When to use it
Programming
Quickly turn a hex constant into decimal, or read a binary flag value while debugging.
Color codes
Convert between a decimal channel value and the hex used in CSS or design tools.
Bitwise & electronics
Inspect register values, masks and bit patterns when working with hardware or low-level code.
Learning
See how the same number looks across bases to understand positional notation.
Notes
- Only non-negative whole numbers are supported; a leading minus is ignored.
- Hexadecimal output uses uppercase A–F.
- There is no practical size limit — arbitrarily large integers work.
- All conversion happens on your device; the number is never sent anywhere.
FAQ
- How do I convert binary to decimal?
- Select BIN as the input base, type the binary digits, and read the decimal value in the DEC row. The reverse works the same way — pick DEC and read BIN.
- What is hexadecimal used for?
- Hex (base 16) is a compact way to write binary: each hex digit equals four bits. It is common for colors (e.g. #FF8800), memory addresses and byte values.
- Can it handle very large numbers?
- Yes. The converter uses BigInt internally, so it stays exact even for numbers much larger than 64 bits.
- Can I paste numbers with 0x or 0b prefixes?
- Yes. Prefixes 0x, 0b and 0o, as well as underscores used as separators, are stripped automatically before conversion.
- Is my data sent to a server?
- No. The conversion runs entirely in your browser and nothing you type leaves your device.