Number Base Converter – Binary, Decimal, Hex, Octal Online Free
Number Base Converter is a free online tool for converting numbers between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). Type a value in any field and all four representations update instantly. Includes 8, 16, and 32-bit binary representations and a quick reference table for values 0–15.
How to Convert Number Bases Online
- 01
Enter a number
Type a value in any of the four fields — binary, octal, decimal, or hexadecimal. The other fields update instantly.
- 02
See all conversions
All four base representations appear simultaneously. For integers, the 8, 16, and 32-bit binary formats are also shown.
- 03
Copy the result
Click the copy icon next to any field to copy that value to the clipboard. Use the quick reference table for manual lookups.
Features
- ✓Bidirectional: type in any base field
- ✓Binary, octal, decimal, and hexadecimal
- ✓8, 16, and 32-bit binary representations
- ✓Two's complement for negative numbers
- ✓One-click copy for each field
- ✓Quick reference table (0–15)
- ✓100% client-side — no network requests
- ✓No login required
Frequently Asked Questions
What number bases does this converter support?
The converter supports four bases: binary (base 2, digits 0–1), octal (base 8, digits 0–7), decimal (base 10, digits 0–9), and hexadecimal (base 16, digits 0–9 and A–F). You can type into any field and all other fields update instantly.
Can I convert negative numbers?
Yes. Type a negative decimal number (e.g., -42) and the tool will produce the correct negative representation in binary, octal, and hex. The 8/16/32-bit binary representations show the two's complement encoding used by computers.
What are the 8-bit, 16-bit, and 32-bit representations?
These show how the number is stored in binary memory at different integer sizes. Positive numbers are padded with leading zeros. Negative numbers use two's complement encoding, which is how CPUs natively represent signed integers.
Do I need to include the 0x or 0b prefix when entering a hex or binary value?
No. The prefix is shown as a static label next to the input field. You only need to type the digits — for example, type "FF" for hex 255, not "0xFF". If you paste a value with a prefix, it will be stripped automatically.
Is there a limit on how large the numbers can be?
The converter uses JavaScript's native parseInt and toString, which supports integers up to 2^53 − 1 (Number.MAX_SAFE_INTEGER). For most programming use cases this is sufficient. Very large numbers beyond this range may lose precision.