Number Base Converter
Convert binary, octal, decimal & hex instantly.
100% private — runs in your browser, nothing is uploaded.
Tip: works with very large whole numbers (arbitrary precision). Fractions and negatives are not supported.
How to use the Number Base Converter
- 1Pick a field
Choose the base you already have a number in — binary, octal, decimal or hex.
- 2Type the number
Enter your value; only valid digits for that base are accepted.
- 3Read every base
The other three fields update instantly with the converted value.
- 4Copy the result
Use the copy button on any field to grab the exact value.
Examples
| Input | Output |
|---|---|
11111111 (binary) | 255 decimal · 377 octal · FF hex |
255 (decimal) | 1111 1111 binary · FF hex |
FF (hex) | 255 decimal · 1111 1111 binary |
Free online number base converter
This number base converter translates a whole number between the four bases programmers use every day: binary, octal, decimal and hexadecimal. Type into any field and the other three update instantly, so you never have to do the math by hand.
The four number systems
- Binary (base 2) — only 0 and 1; how computers store everything at the lowest level.
- Octal (base 8) — digits 0–7; still seen in Unix file permissions.
- Decimal (base 10) — the everyday numbers people use.
- Hexadecimal (base 16) — 0–9 then A–F; compact for colors, memory addresses and byte values.
Why convert between bases?
Hex and binary show up constantly in low-level code, color codes like #FF8800, bit masks and network addresses. Being able to jump between them quickly saves time and avoids mistakes. Because everything runs in your browser with arbitrary-precision math, the tool is instant, exact and works offline.
Frequently Asked Questions
How do I convert binary to decimal?
Type a binary number in the Binary field and the decimal value updates instantly in the Decimal field, along with octal and hexadecimal. For example, binary 11111111 is 255 in decimal.
How do I convert decimal to hexadecimal?
Enter your number in the Decimal field and read the Hexadecimal field. For example, 255 becomes FF and 3000 becomes BB8.
What are binary, octal, decimal and hexadecimal?
They are number systems with different bases: binary is base 2 (digits 0–1), octal is base 8 (0–7), decimal is base 10 (0–9) and hexadecimal is base 16 (0–9 and A–F). Computers use binary and hex heavily.
Can it handle very large numbers?
Yes. The converter uses arbitrary-precision integers, so even numbers with hundreds of digits convert exactly without rounding errors.
Why is the binary grouped in sets of four?
Grouping binary into nibbles (four bits) and hex into pairs (bytes) makes long values far easier to read. The spaces are only for display and are ignored when you type.
Does it support negative numbers or fractions?
This converter focuses on non-negative whole numbers, which covers the vast majority of base-conversion needs in programming. Fractions and negatives are not supported.