Convert between binary, octal, decimal and hexadecimal — or any base from 2 to 36 — instantly as you type, with built-in validation.
🔒 100% private — nothing is uploaded
Binary base 2
Octal base 8
Decimal base 10
Hexadecimal base 16
Any base
How it works
A number's value is the same no matter how it's written — only the base (the count of distinct digits) changes. This tool reads your input in its source base, then re-writes that exact value in every other base.
1
Pick the source base
Tell us how to read your input — binary, octal, decimal, hex, or any base from 2 to 36. Digits use 0–9 then A–Z.
2
Type your number
Conversions update live as you type. Invalid digits for the chosen base are flagged straight away, so you never get a silent wrong answer.
3
Copy any result
Grab binary, octal, decimal, hex, or a custom base with one click. Big numbers are handled exactly using BigInt — no precision loss.
🔒
Private by design. Every conversion runs entirely in your browser with plain JavaScript. Your numbers are never sent anywhere — we never see them.
Frequently Asked Questions
Which number bases can I convert between?▼
Binary (base 2), octal (base 8), decimal (base 10) and hexadecimal (base 16) are always shown, plus any custom base from 2 to 36 for both the input and an extra output. Digits run 0–9 and then A–Z, which is why 36 is the maximum.
Which digits are valid for each base?▼
A base uses exactly as many digit symbols as its value. Binary allows only 0 and 1; octal 0–7; decimal 0–9; hexadecimal 0–9 and A–F. In general a base-N number may use the digits 0 up to N−1. Anything outside the range for the chosen base is flagged instead of being silently misread.
Does it use two's complement for negative numbers?▼
No. Values are treated as unsigned magnitudes — there is no fixed bit width and no two's-complement wrap-around. If you type a leading minus sign it's preserved, so the binary or hex output shows a plain - in front rather than a two's-complement bit pattern.
Can it handle very large numbers?▼
Yes. Conversions use BigInt internally, so arbitrarily large whole numbers convert exactly with no loss of precision — unlike ordinary floating-point maths, which loses accuracy past about 2⁵³.
What is base conversion used for?▼
It's everyday work in programming and electronics: reading hex colour codes and memory addresses, inspecting binary flags and bitmasks, working with octal file permissions, or simply checking what a decimal value looks like in another base. Everything runs in your browser — nothing you type is uploaded.