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Free Base Converter (Base 2-36)

Convert a number between any two bases from 2 to 36.

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Binary, octal, decimal, and hexadecimal cover the most common cases, but some contexts — like base-36 identifiers or unusual encoding schemes — need a base beyond those four.

This converter handles any base from 2 to 36, using digits 0-9 and then letters a-z for bases above 10.

How it works

Enter a value along with its current base and the base you want to convert it to (both between 2 and 36). The converter treats the value as a number in the source base, converts it to base 10 internally, then converts that to the target base.

  1. Enter value.
  2. Enter from base (2-36).
  3. Enter to base (2-36).
  4. Click Calculate to see your results.

Examples

Converting "z" from base 36 to base 10

The digit "z" in base 36 represents the value 35, since z is the 36th possible digit (0-9 then a-z).

Who should use it

  • Converting a base-36 identifier (common in URL shorteners) to a decimal number.
  • Working with an unusual base encoding used by a specific system or protocol.

Industry applications

  • Software development and computer science education
  • URL shortener and unique identifier systems

Advantages

  • Supports the full range of bases from 2 to 36, not just the four common ones.
  • Validates that every digit is actually valid for the specified source base.

Limitations

  • Limited to values up to 64 characters long.

Common mistakes to avoid

  • Entering a digit that isn't valid for the specified source base (like using "8" in an octal or binary number).
  • Confusing uppercase and lowercase letters — this converter treats them the same, but not all systems do.

Best practices

  • Double-check which base your source value is actually in before converting — an incorrect source base produces a technically valid but wrong result.

Tips

  • Base 36 is a common choice for compact, human-typeable identifiers (like URL shortener codes) since it uses every digit and letter of the alphabet — this converter is handy for decoding those back to a plain decimal number.

Frequently asked questions

Yes, with no signup and no limit on how many conversions you run.
The Number Base Converter is limited to the four most common bases (binary, octal, decimal, hexadecimal); this converter supports any base from 2 to 36.
After 0-9, letters a through z are used as digits, so base 16 uses 0-9 and a-f, base 36 uses 0-9 and a-z (the maximum possible with single alphanumeric characters).
The converter rejects it and tells you which digit isn't valid for that base — for example, entering "9" as a binary (base 2) number would be rejected, since binary only uses 0 and 1.

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