Convert numbers between binary, octal, decimal and hexadecimal — or any custom base from 2 to 36 — with ZeroFee Tools' free number base converter. Conversions happen live as you type, handle arbitrarily large integers exactly (including negatives), and every output has a one-click copy button. Also includes a binary-to-text mode and a full 0–255 reference table. No signup, no watermark, no limits.
Prefixes like 0x, 0o and 0b are accepted when they match the selected base. Arbitrarily large integers convert exactly — no rounding, no limits.
11111111
377
255
ff
73
Showing base 36
Binary is grouped in 8-bit bytes separated by spaces. Multi-byte UTF-8 characters (é, 中, emoji) are handled correctly.
Conversion reference: 0–255
Decimal, hexadecimal, octal, binary and ASCII for every byte value — generated instantly in your browser.
| Dec | Hex | Oct | Binary | ASCII |
|---|
How do I convert binary to decimal?
Short answer: Type the binary number in the Value field, set “From base” to Binary (2), and read the decimal result instantly — for example, 1010 becomes 10.
- Enter your number in the Value field.
- Set From base to the base your number is written in (Binary, Octal, Decimal, Hexadecimal, or a custom base 2–36).
- All outputs update live: binary, octal, decimal, hexadecimal and your custom target base.
- Click Copy on any output to copy it to your clipboard.
What is hexadecimal used for?
Short answer: Hexadecimal (base 16) is shorthand for binary: each hex digit represents exactly 4 bits, so programmers use it for memory addresses, color codes like #FF5733, and debugging.
Because 16 is a power of 2, converting between binary and hex is trivial — group binary digits in fours. Octal (base 8) works the same way with groups of three and shows up in Unix file permissions like 755.
How do I convert text to binary?
Short answer: Open the “Binary ⇆ Text” tab, choose Text → Binary, and type. Each character is encoded as UTF-8 bytes shown in 8-bit groups — “Hi” becomes 01001000 01101001.
To decode, switch to Binary → Text and paste grouped binary back. The bit length must be a multiple of 8, and only the digits 0 and 1 (plus spaces) are accepted.
Last updated: October 15, 2026.
Frequently asked questions
Is this base converter free and unlimited?
Yes. Convert as many numbers as you like, of any size: no account, no watermark, no limits. All conversions run in your browser.
Which number bases are supported?
Any base from 2 to 36, with one-click presets for binary (2), octal (8), decimal (10) and hexadecimal (16). Type a custom base such as 12 or 36 for anything in between.
Can it handle very large numbers?
Yes. Conversions use arbitrary-precision integers, so values far beyond normal calculator limits (hundreds of digits) convert exactly with no rounding.
What happens if I type an invalid digit?
The converter shows an inline error naming the offending digit — for example, typing “2” while binary is selected. Fix the digit or switch the “from” base.
How does the binary-to-text mode work?
Text is encoded as UTF-8 bytes and shown as 8-bit binary groups; paste grouped binary back to decode it into text. Multi-byte characters such as accented letters and emoji are handled correctly.
Is my data private?
Yes. Every conversion happens locally in your browser; nothing you type is sent to a server or stored.