ToolNestFree Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal — or any base from 2 to 36. Type a value once and see it in every common base simultaneously, with input validation so mistyped digits get flagged instead of silently misconverted.
—Binary
—Octal
—Decimal
—Hexadecimal
✓ Free forever · ✓ No signup · ✓ Runs in your browser — your data never leaves your device.
How to Use the Number Base Converter
- Type your number and select the base it's written in.
- Click Convert — binary, octal, decimal, and hex appear at once.
- Invalid digits for the chosen base are flagged immediately.
- Copy any result straight into your code.
Why Use Our Number Base Converter?
- All bases at once — one input, four simultaneous outputs.
- Bases 2–36 — binary through hex and beyond.
- Input validation — catches digits that don't exist in the source base.
- CS-homework friendly — free, instant, shows every step's result.
Frequently Asked Questions
What is hexadecimal used for?
Colors (#FF5733), memory addresses, and byte values — base-16 packs 4 bits per digit, so it's compact and readable.
How do I convert binary to decimal by hand?
Sum the place values of each 1 bit: 1011 = 8+0+2+1 = 11.
Why do programmers use octal?
Mostly Unix file permissions (chmod 755) — each octal digit maps to 3 permission bits.
What bases are supported?
2 through 36 (digits 0–9 plus letters A–Z).
Is it free?
Yes — free forever, no signup.