What is the Number Base Converter?
Computers think in binary, humans think in decimal, and programmers live somewhere in between — reading memory addresses in hexadecimal, file permissions in octal, and bitmasks in binary. Converting between these bases by hand is tedious and error-prone, yet it comes up constantly: decoding a hex dump, setting a subnet mask, understanding a Unix permission like 755, or working through a computer science exam. A base converter turns that mental arithmetic into an instant, trustworthy result.
This converter translates any number between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) the moment you type. It validates your input for the selected base — so an accidental '9' in a binary field gets flagged immediately instead of silently producing garbage. Everything runs locally in your browser with no uploads and no accounts, making it a fast companion for debugging sessions, coursework, and certification prep.
How to use it
- Enter your number — Type the number you want to convert into the input field — digits only, no prefixes like 0x needed.
- Select the source base — Choose whether your input is binary, octal, decimal, or hexadecimal using the base selector.
- See all conversions — All four base representations appear instantly side by side, updating live as you type or edit.
- Check input validity — Invalid digits for the chosen base are flagged immediately — for example, 2-9 are illegal in binary.
- Copy any result — Click any output value to copy it, ready to paste into code, documentation, or a terminal command.
Common use cases
- Convert the octal permission 755 to binary to understand exactly which read/write/execute bits are set.
- Translate a hexadecimal memory address from a crash log into decimal for a bug report.
- Convert a binary subnet mask like 11111111.11111111.11111111.00000000 into the familiar /24 CIDR notation basis.
- Turn a decimal color-adjacent value into hex while learning how RGB channels map to hex color codes.
Tips
- Prefix hex values with 0x in code but not in the converter — the tool knows the base from your selection.
- For fractional numbers, remember only the integer part converts cleanly; fractions need separate handling.
- When converting large hex values, group digits in fours (nibbles) to make the binary mapping obvious.
- Double-check endianness when converting multi-byte hex dumps — byte order changes the decimal meaning entirely.
Frequently asked questions
What number bases are supported?
Binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) — the four bases developers encounter most often in programming, networking, and systems work.
Why does my binary input show an error?
Binary only allows the digits 0 and 1. Any other digit — even a 2 — is invalid in base 2, and the tool flags it so you can fix the input.
Can it handle very large numbers?
Yes, within reasonable limits. Because conversion runs locally with arbitrary-precision arithmetic, even 64-bit and larger values convert accurately.
Is hexadecimal case-sensitive here?
No. Both uppercase (FF) and lowercase (ff) hex digits are accepted, and the output uses a consistent format you can copy anywhere.