Number Base Converter
Convert between binary, decimal, octal, and hexadecimal instantly — type once, see every base update live.
Instant & live
Every base updates as you type — no "Convert" button, no waiting.
Validated input
Only valid characters for the selected base are accepted — no silent garbage results.
Private by design
Runs entirely in your browser. Nothing is ever uploaded or logged.
Convert Number Bases Online
CurePDF's number base converter converts a value between binary (base 2), decimal (base 10), octal (base 8), and hexadecimal (base 16) simultaneously — enter a value in any one base and see the equivalent in all four immediately.
How Number Base Conversion Works
Every positional number system represents a value as a sum of digits multiplied by increasing powers of its base. Converting from decimal to another base repeatedly divides by the target base and reads the remainders; converting to decimal multiplies each digit by its place value and sums the results.
Valid Characters Per Base
| Base | Valid characters |
|---|---|
| Binary | 0, 1 |
| Octal | 0–7 |
| Decimal | 0–9 |
| Hexadecimal | 0–9, A–F (case-insensitive) |
This converter validates your input against the selected base's valid characters as you type — a binary field won't silently accept a "2," for example.
Who Uses a Number Base Converter?
Programmers
Reading memory addresses, color codes, and bitwise flags, which are usually written in hex.
Computer science students
Learning how positional number systems work, from binary logic to hex shorthand.
Network engineers
Working with subnet masks and IP-related values, often expressed in binary or hex.
Embedded/low-level developers
Working directly with register values and byte-level data.
Common Mistakes When Converting Number Bases
- Assuming hex is case-sensitive. It isn't — "ff" and "FF" represent the same value.
- Forgetting binary has no digits above 1. A binary string containing a "2" or higher isn't a larger binary number — it's invalid.
- Losing precision on very large numbers. Values beyond JavaScript's safe integer range (2^53 − 1) can lose precision in any browser-based converter, including this one.
Frequently Asked Questions
How do I convert decimal to binary?
Repeatedly divide the decimal number by 2 and record the remainders; reading the remainders in reverse gives the binary value. This converter does that instantly -- for example, decimal 10 is binary 1010.
How do I convert binary to decimal?
Multiply each binary digit by 2 raised to its position (counting from 0 on the right) and add the results. For example, binary 1010 = (1x8)+(0x4)+(1x2)+(0x1) = 10.
What characters are valid in hexadecimal?
Hexadecimal uses 0-9 and A-F (case-insensitive), representing values 0 through 15 per digit.
Why is 255 equal to FF in hex?
255 is the largest value a single byte (8 bits) can hold. In hexadecimal, two digits (base 16) can represent exactly the same range: F x 16 + F = 255, so 255 decimal = FF hex.