Base36

Base36 represents numbers with 36 characters (0-9 and a-z), mixing digits and letters, and is commonly used for short links and compact IDs.

Purpose

It expresses large integers more compactly than decimal, in all-lowercase alphanumeric form, producing URL-friendly short codes.

Mechanism

A non-negative integer is repeatedly divided by 36; remainders 0-9 map to characters 0-9 and 10-35 map to a-z. Decoding expands by positional weight. It applies to integers only, not byte streams.

Use cases

Short-link generation (YouTube video IDs use a Base64 variant, but Base36 is simpler)
Compact database primary key representation
Invitation and redemption codes
Flickr short URLs

Examples

Input
```
1234567890
```
Output
```
kf12oi
```
Decimal to Base36

Common errors

Applying it to negative or floating-point numbers: Base36 is defined only for non-negative integers

Related terms

Base62 represents numbers with 62 characters (0-9, a-z, A-Z); it is case-sensitive, denser than Base36, and widely used for short links and ID generation.

Base58 is a human-oriented binary-to-text encoding using 58 characters (dropping the easily confused 0, O, I, l, +, and / from Base64), best known for cryptocurrency addresses.

Hexadecimal (hex) is the base-16 numeral system, using 0-9 and A-F for 0-15; it is one of the most common radix notations in computing.

Related tools

Convert numbers between any base (2-36). Free, private, 100% client-side.

Random Bytes Generator

Generate cryptographically secure random bytes or integers. Free, private, and 100% client-side.

Base36 Encode — pure client-side tool. Privacy-first, no server round-trip.

Base36 Decode — pure client-side tool. Privacy-first, no server round-trip.

References