Number Base Converter
Convert between binary, octal, decimal and hexadecimal instantly — see all four at once.
Convert numbers between bases instantly
The Number Base Converter converts a number between binary, octal, decimal, and hexadecimal — all at once. Enter a value, tell it which base the value is in, and see the equivalent in every other base immediately, each with one-click copy. It is an everyday helper for programmers, students, and anyone working close to the metal.
What are number bases?
A number base (or radix) is how many distinct digits a system uses. Decimal (base 10) uses 0–9 and is what we count with. Binary (base 2) uses only 0 and 1, the language of computers. Hexadecimal (base 16) uses 0–9 and A–F, a compact way to write binary. Octal (base 8) uses 0–7 and appears in things like Unix file permissions. The same quantity can be written in any base.
How the bases relate
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 10 | 1010 | 12 | A |
| 16 | 10000 | 20 | 10 |
| 255 | 11111111 | 377 | FF |
| 256 | 100000000 | 400 | 100 |
How to use it
- Enter your number in the field.
- Select which base your input is in.
- Read the equivalent in all four bases, and copy whichever you need.
Why programmers care about bases
Computers store everything in binary, but binary is hard for humans to read, so hexadecimal is used as a shorthand — each hex digit maps to exactly four binary digits. Colors (#FF8800), memory addresses, byte values, and bitmasks are all commonly written in hex. Octal still shows up in Unix file permissions like chmod 755. Being able to flip between bases quickly is a core skill for low-level and systems work.
Tips
- Each hex digit equals 4 binary digits — handy for reading bytes (2 hex digits = 1 byte).
- 255 is the largest value in a single byte, written as FF in hex.
- You can paste hex with or without a leading
0x.
Private and free
All conversions are computed in your browser. Nothing is uploaded, there are no limits, and it is completely free.
Frequently asked questions
How do I convert binary to decimal?
Enter the binary number and choose 'From Binary'. The decimal value appears instantly, along with octal and hex.
What is hexadecimal used for?
Hex is a compact way to represent binary. It is used for colors, memory addresses, byte values, and bitmasks.
Can I paste hex with 0x?
Yes. A leading 0x is automatically ignored when you convert from hexadecimal.
Is it free and private?
Yes. All conversions run in your browser with nothing uploaded, and it is completely free.