What characters are valid in base-36?

The digits 0–9 and the letters A–Z (or a–z — base-36 is case-insensitive). Any other character, such as a space, hyphen, or punctuation mark, is not valid and will trigger an error message.

Is base-36 the same as hexadecimal?

No. Hexadecimal (base-16) uses 16 symbols: 0–9 and A–F. Base-36 extends the alphabet all the way to Z, giving 36 symbols. Base-36 can represent larger values in fewer characters than hex when the character set is restricted to alphanumerics.

What is the largest base-36 number this tool can handle?

The tool uses JavaScript's built-in BigInt, so there is no practical upper limit. Strings of 20 or more characters are computed accurately without floating-point precision loss.

How do I convert decimal back to base-36?

Use our Decimal to Base36 converter (search "decimal to base36" on the site). The algorithm repeatedly divides the decimal number by 36 and maps remainders to the base-36 alphabet.

Why does JavaScript use base-36?

JavaScript's Number.prototype.toString(36) outputs a number in base-36, and parseInt("...", 36) parses it back. This makes base-36 a common choice for generating short, URL-safe alphanumeric identifiers from numeric seeds.

Base36 to Decimal Converter

Name: Base36 to Decimal Converter
Availability: InStock
Author: Nham Vu

Type any base-36 number (digits 0–9 and letters A–Z) and instantly see the equivalent decimal value.

Base-36 Number

Enter a base-36 value to see the decimal result.

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Summary

Type any base-36 number (digits 0–9 and letters A–Z) and instantly see the equivalent decimal value.

How it works

Enter a base-36 value in the input field (digits 0–9 and letters A–Z are valid).
The tool parses each character and maps it to its digit value (0–9 → 0–9, A/a → 10, B/b → 11, … Z/z → 35).
Each digit value is multiplied by 36 raised to the power of its position (right-to-left, starting at 0).
All positional products are summed to produce the final decimal result.
The step-by-step breakdown panel shows every positional calculation so you can follow the math.
Use Batch Mode to convert multiple base-36 values at once, one per line.

Use cases

Decode compact URL shortener IDs back to their underlying numeric IDs.
Interpret base-36 encoded timestamps or sequence numbers in logs.
Verify hand-calculations when learning numeral system conversions.
Decode unique alphanumeric tokens generated by libraries like nanoid.
Cross-check base-36 output from programming languages (e.g. parseInt in JS, toString(36) in Python).
Batch-decode a list of base-36 tokens exported from a database.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu