Number Base Converter
Type a number in any base and watch every other base update as you type. Edit Binary, Octal, Decimal, or Hexadecimal — or any custom base from 2 to 36 — and the rest convert instantly on one screen. Tap any value to copy it. Everything runs in your browser, so your numbers never leave the page.
What is the Number Base Converter?
The Number Base Converter is a free online tool that translates a whole number between the four bases programmers use every day — binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16) — plus any custom base from 2 to 36. Type a value into any field and every other field updates the moment you type, so you never have to press a "convert" button or jump between separate single-direction pages.
How to use it
- Pick the field that matches the number you already have — Binary, Octal, Decimal, or Hexadecimal.
- Type the number. Invalid digits for that base are flagged, so you can't accidentally put a 2 in the binary box or a G in the hex box.
- Read the other three fields — they convert live as you type.
- Need an unusual base? Set a base (2-36) in the custom radix box and type a value beside it.
- Tap any Copy button to grab the result. One glance, done — no sign-up, nothing to install.
The method behind it
Every positional number system works the same way: each digit is multiplied by the base raised to the digit's position, counting from zero on the right. Binary 1011 is (1x2³)+(0x2²)+(1x2¹)+(1x2⁰) = 8+0+2+1 = 11. To go the other way, the tool repeatedly divides the decimal value by the target base and reads the remainders bottom-to-top. Bases above 10 borrow letters (A=10 … F=15 … up to Z=35) as extra digits.
Examples
- Binary
11111111→ Decimal255→ HexFF(one full byte). - Decimal
3000→ HexBB8→ Octal5670. - Hex
1A→ Binary11010→ Decimal26.
Base reference table
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 |
| 8 | 1000 | 10 | 8 |
| 10 | 1010 | 12 | A |
| 15 | 1111 | 17 | F |
| 16 | 10000 | 20 | 10 |
| 255 | 11111111 | 377 | FF |
| 256 | 100000000 | 400 | 100 |
Common use cases
- Students checking homework on positional number systems.
- Developers reading memory addresses, byte values, or color codes in hex.
- Network engineers translating subnet masks and IP octets.
- Debugging bit flags, permissions (octal), or file modes.
- Quick sanity checks while writing low-level or embedded code.
Why use this one
Most ranking pages only convert one direction at a time. This one shows all four bases live on a single screen, adds a custom 2-36 radix, runs 100% in your browser (your values never leave the page), and needs no account. Faster, more private, and more flexible than the single-direction calculators. When you need a different kind of conversion, try our Roman Numeral Converter or Hex to RGB tool.
Frequently asked questions
How do I convert binary to decimal?
Type your binary digits (only 0s and 1s) into the Binary field and the Decimal field updates instantly. Internally each binary digit is multiplied by a power of 2 and the results are summed — for example 1011 = 8 + 0 + 2 + 1 = 11 in decimal.
What is hexadecimal and why is it used?
Hexadecimal is base 16, using digits 0-9 and letters A-F. Programmers use it because one hex digit maps cleanly to four binary bits, making long binary values short and readable — common in memory addresses, color codes, and byte values.
What is the highest base this converter supports?
The custom radix field supports any base from 2 up to 36. Bases above 10 use letters A-Z as extra digits, so base 36 uses 0-9 then A-Z, the maximum that fits standard alphanumeric digits.
Does the converter handle negative numbers or decimals?
This tool converts non-negative whole numbers (integers). Fractional parts and signed or two's-complement representations are not converted, since those vary by system and word size.
Is my data sent to a server?
No. Every conversion runs entirely in your browser using JavaScript. Nothing you type is uploaded, logged, or stored, so it is safe for sensitive values and works even offline once the page has loaded.