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Number Base Converter

Convert numbers between decimal, binary, octal and hexadecimal in a live 4-row grid. BigInt-safe with optional signed 32 / 64-bit mode.

Free No signup Client-side Privacy friendly
Sign mode

How to use

  1. 1 Type a number in any of the four rows — the others update live.
  2. 2 Pick Unsigned for arbitrary-precision BigInt, or Signed 32-bit / 64-bit for two's-complement display of negatives.
  3. 3 Toggle the prefix switch to show 0b, 0o, 0x where relevant.
  4. 4 Copy any row to the clipboard with its Copy button.

Why use this tool

  • BigInt-safe — numbers larger than 2^53 do not lose precision.
  • Two's-complement display for signed 32 / 64-bit modes.
  • No prefixes required on input — paste -42, 0b1010, 0xFF, or plain digits.
  • Runs in your browser, zero network calls.

Frequently asked questions

Why does -1 show as ffffffff in signed 32-bit?

That is the two's-complement representation of -1 at 32 bits. Switch back to Unsigned to see the decimal -1 as just -1, with binary 1.

How large can the number get?

In Unsigned mode the only limit is browser memory — it uses BigInt internally. Signed modes mask to 32 or 64 bits.

Can I paste a number with underscores or spaces?

Yes — common digit-grouping separators like 1_000_000 or 1 000 000 are accepted.

Need bitwise operations on these numbers?

Use our Bitwise Calculator — AND, OR, XOR, NOT, shifts in any of the four bases.

Summary

Number Base Converter is a free developer utility by Zerethon Tools. Convert numbers between decimal, binary, octal and hexadecimal in a live 4-row grid. BigInt-safe with optional signed 32 / 64-bit mode. Runs entirely in the browser — no signup, no upload.

Category
Developer
Pricing
Free
Privacy
Browser-based
Signup
Not required

Privacy

Your data never leaves your browser unless explicitly stated. Number Base Converter runs entirely client-side — no server upload, no logging, no tracking of your input.

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