Number & Data

Number Base Converter

Convert numbers between any base from 2 to 64 with BigInt-powered arbitrary precision.

or custom
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or custom
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How to use this tool

  1. Set the Source Base to the base your number is currently in — pick from the dropdown (Binary, Octal, Decimal, Hexadecimal, 36, 62, 64) or type any base from 2 to 64 in the custom field.
  2. Type or paste your number into the Input Number box.
  3. Set the Target Base to the base you want to convert into.
  4. The result appears instantly in the read-only box beneath it — no button press needed.
  5. Use Copy Result to copy the output, Copy to copy your input, or Clear to reset and start over.

Why this tool is helpful

Convert between any bases

Move between binary, octal, decimal, hexadecimal, and higher bases like 36, 62, and 64 in one place — no calculator or script needed.

Handle arbitrarily large numbers

Because it uses JavaScript BigInt, values far beyond Number.MAX_SAFE_INTEGER convert exactly — no silent overflow or precision loss.

Work with non-standard bases

Base 62 is used by URL shorteners, and the 64-character alphabet (0-9 A-Z a-z + /) matches Base64-style digit sets.

Use any custom base from 2–64

The dropdown covers common bases, but you can type any base between 2 and 64 into the custom field for less common conversions.

Keep sign and exactness intact

Negative numbers (leading -) are preserved through conversion, and results are exact integers rather than rounded floats.

Stay private

Everything runs in your browser. Nothing is uploaded, logged, or sent to a server — safe for identifiers, hashes, and other sensitive values.

FAQ

What does this tool do?

It converts a whole number from one base to another, for any base between 2 and 64. You pick the source and target bases, type a number, and the converted value appears instantly.

How does it handle very large numbers?

All arithmetic uses JavaScript BigInt, which has arbitrary precision. Numbers larger than what a normal 64-bit integer can hold convert exactly, with no overflow.

What alphabet does it use for digits?

A 64-character alphabet: 0-9, A-Z, a-z, then + and /. For base N, only the first N characters are valid digits — so base 16 uses 0-9 A-F.

Why do I get "Invalid input"?

That means your number contains a character that isn't a valid digit in the source base — for example, a 9 in binary, or a character outside the alphabet. Check that the Source Base matches your number.

Can it handle negative numbers or fractions?

Negative numbers are supported via a leading - sign. Fractions and decimals are not — only whole integers are converted, so a . will be treated as invalid.

Can I use a base that isn't in the dropdown?

Yes. Type any integer from 2 to 64 into the "or custom" field next to either the source or target base dropdown.

Does any of my data leave my browser?

Never. All conversion happens locally in JavaScript. Your input is not sent to, stored on, or logged by any server.