Number Base Converter
Convert between decimal, binary, octal, and hexadecimal instantly. Great for programming, networking, electronics, and learning how computer number systems work.
Supports signed whole numbers. Type in decimal, binary, octal, or hex and the other bases update instantly.
Decimal
Base 10
Binary
Base 2
Octal
Base 8
Hexadecimal
Base 16
Bit Representations
Two's complement output for common integer sizes.
8-bit
Out of signed rangeNot representable in this signed integer size.
16-bit
0000 0000 1111 1111
32-bit
0000 0000 0000 0000 0000 0000 1111 1111
64-bit
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 1111 1111
ASCII Character
Printable ASCII is available for decimal values 32 through 126.
Character
—
Not a printable ASCII character
Quick Tips
- Binary uses only 0 and 1, which makes it ideal for computers.
- Octal groups binary digits into sets of 3 bits.
- Hex groups binary digits into sets of 4 bits, so one hex digit maps neatly to a nibble.
- 255 decimal equals FF hex, 377 octal, and 11111111 binary.
Common Values Reference
Handy checkpoints for powers of two, byte limits, and familiar hex constants.
| Decimal | Binary | Octal | Hex | Why it matters |
|---|---|---|---|---|
| 15 | 1111 | 17 | F | 4-bit max value |
| 16 | 10000 | 20 | 10 | 2⁴ |
| 31 | 11111 | 37 | 1F | 5-bit max value |
| 32 | 100000 | 40 | 20 | 2⁵, ASCII space |
| 64 | 1000000 | 100 | 40 | 2⁶, @ symbol |
| 127 | 1111111 | 177 | 7F | 7-bit max / DEL |
| 255 | 11111111 | 377 | FF | 8-bit max (0xFF) |
| 1024 | 10000000000 | 2000 | 400 | 2¹⁰ |
| 4096 | 1000000000000 | 10000 | 1000 | 2¹² |
| 65535 | 1111111111111111 | 177777 | FFFF | 16-bit max |
How to Use
- Choose the base you want to type in: decimal, binary, octal, or hexadecimal.
- Enter a whole number and the calculator will convert it to all four bases instantly.
- Use the copy buttons to grab any output for code, terminal work, or documentation.
- Check the bit-width section to see 8-bit, 16-bit, 32-bit, and 64-bit two's complement representations.
- Review the ASCII and common values sections for quick reference while debugging or studying.
Frequently Asked Questions
What is the difference between binary, octal, decimal, and hexadecimal?
Decimal is base 10 and uses digits 0 through 9. Binary is base 2 and uses only 0 and 1. Octal is base 8 and uses digits 0 through 7. Hexadecimal is base 16 and uses digits 0 through 9 plus A through F.
Why is hexadecimal used so often in programming?
Hexadecimal is compact and maps neatly to binary because each hex digit represents exactly 4 bits. That makes it easier to read memory addresses, color values, byte data, and machine-level values without writing long binary strings.
How do I convert binary to decimal?
Each binary digit represents a power of 2. Starting from the right, add the values for every position that contains a 1. For example, 1101 binary equals 8 + 4 + 1, which is 13 decimal.
What does 0xFF mean?
0xFF is hexadecimal notation for 255 decimal. The 0x prefix tells you the value is written in base 16, and FF means 15×16 + 15.