Number Base Converter Guide: Binary, Hex & More

Q: How do I convert decimal to binary?

Repeatedly divide the decimal number by 2 and record the remainders; reading the remainders from last to first gives the binary value. The converter does this instantly in either direction.

Q: Why do programmers use hexadecimal?

Hex is compact and maps neatly onto binary: each hex digit is exactly four bits, so a byte is two hex digits. That makes colours, memory addresses and byte values much easier to read than long binary strings.

Q: Is anything uploaded?

No. All conversions run in your browser; the numbers you enter are never sent to a server.

What this tool does

The Number Base Converter converts a whole number between binary, octal, decimal, hexadecimal and any base from 2 to 36. Type in any field and the others update instantly. It uses arbitrary-precision arithmetic, so huge numbers stay exact, and it all runs in your browser.

What a "base" means

A base is how many distinct digits a system uses. Decimal (base 10) uses 0–9; binary (base 2) uses only 0 and 1; octal (base 8) uses 0–7; and hexadecimal (base 16) uses 0–9 then a–f for ten to fifteen. Each position is worth the base raised to its place, so binary 1011 is 8 + 0 + 2 + 1 = 11 in decimal.

Converting by hand

To a smaller base: divide repeatedly by the target base and read the remainders bottom-up.
From a base to decimal: multiply each digit by the base to the power of its position and add them up.
Binary ↔ hex: group bits in fours — each group is one hex digit — which is why hex is so handy.

How to use it

Open the Base Converter.
Type a value into decimal, binary, octal or hex.
Watch the other fields update live; use the custom-base box for anything from 2 to 36.
Click Copy on whichever representation you need.

Why hexadecimal is everywhere

Each hex digit is exactly four binary bits, so a byte is two tidy hex digits. That's why colours (#ff8800), memory addresses and byte dumps are written in hex — it's compact and lines up with the underlying binary.

Nothing is uploaded

All conversions happen locally in your browser — the numbers you enter are never sent anywhere.

FAQ

How do I convert decimal to binary?

Divide repeatedly by 2 and read the remainders bottom-up — or just type it in and read the binary field.

Why do programmers use hexadecimal?

Because each hex digit is four bits, so it maps cleanly onto binary and stays compact.

Is anything uploaded?

No — it all runs in your browser.

Ready to try it? Open the Number Base Converter →

Number bases, made clear