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Base36 is a binary-to-text encoding that represents binary data in an ASCII string format by translating it into a radix-36 representation. The choice of 36 is convenient in that the digits can be represented using the numerals 0–9 and the letters a-z^[1] (the lowercase ISO basic Latin alphabet).

Each Base36 digit contains log₂(36) ≈ 5.17 bits of information, so six bits is sufficient to represent each digit. Base36 numbers can also be expanded to pairs of senary (base 6) digits.

Signed 32- and 64-bit integers will only hold at most 6 or 13 base-36 digits, respectively (that many base-36 digits can overflow the 32- and 64-bit integers). For example, the 64-bit signed integer maximum value of "9223372036854775807" is "1Y2P0IJ32E8E7" in base-36. Similarly, the 32-bit signed integer maximum value of "2147483647" is "ZIK0ZJ" in base-36.

The C standard library since C89 supports base36 numbers via the strtol and strtoul functions^[2]

In the Common Lisp standard (ANSI INCITS 226-1994), functions like parse-integer support a radix of 2 to 36.^[3]

Java SE supports conversion from/to String to different bases from 2 up to 36. For example, [1] and [2]

Just like Java, JavaScript also supports conversion from/to String to different bases from 2 up to 36. [3]

PHP, like Java, supports conversion from/to String to different bases from 2 up to 36 using the base_convert function, available since PHP 4.

Go supports conversion to string to different bases from 2 up to 36 using the built-in strconv.FormatInt(), and strconv.FormatUint() functions,^[4][5] and conversions from string encoded in different bases from 2 up to 36 using the built-in strconv.ParseInt(), and strconv.ParseUint() functions.^[6][7]

Python allows conversions of strings from base 2 to base 36.^[8]

Raku supports base2 to base36 for all its real numeric types with its builtins: base^[9] and parse-base.^[10]

• Senary – Base-6 numeral system
• Uuencoding

• A discussion about the proper name for base 36 at the Wordwizard Clubhouse
• The Prime Lexicon, a list of words that are prime numbers in base 36
• A Binary-Octal-Decimal-Hexadecimal-Base36 converter written in PHP
• A C# base 36 encoder and decoder
• sample in C# that demonstrates the HexaTriDecimal Numbering System including string parsing, as well as increment/decrement operations