Free exact browser converter
Base36 to Decimal Converter
Convert Base36 integers to decimal online without Number rounding. Accept uppercase or lowercase digits 0–9 and A–Z, and validate the complete value.
Interactive tool
Convert Base36 to Decimal
Ready
Choose a clear output representation.
Detailed conversion guide
How to Convert Base36 to Decimal
Read each Base36 digit as 0–35. Starting from zero, multiply the accumulated integer by 36 and add the next digit. ZZZ therefore means 35×36² + 35×36 + 35 = 46655.
Accumulation uses BigInt throughout. A long Base36 ID stays exact even when the decoded decimal integer exceeds 2^53 − 1. Letters are case-insensitive; zzz and ZZZ both produce 46655.
| Input | Output | Meaning |
|---|---|---|
0 | 0 | zero |
Z | 35 | last single digit |
ZZZ | 46655 | 36³ − 1 |
2GOSA7PA2GX | 9007199254740993 | above Number precision |
Decode Base36 with BigInt Accumulation
The algorithm validates the representation before exact integer conversion, so malformed input never produces a plausible partial answer.
const digits = input.trim().replace(/[\s_]/g, "").toUpperCase();
if (!/^[0-9A-Z]+$/.test(digits)) throw Error("Invalid Base36");
let n = 0n;
for (const c of digits) n = n * 36n + BigInt(parseInt(c, 36));
const decimal = n.toString(10);Base36 Letters and Prefix-Like Values
All letters A–Z are valid numeric digits, so a word such as HELLO is interpreted as a Base36 number. It is not decoded into text. Signs, fractions, and punctuation are rejected.
Base36 has no prefix here: 0x is a valid Base36 value equal to decimal 33, and is not a hex prefix. Leading zeros are ignored numerically. Spaces and underscores join one value rather than separate multiple IDs.
Related converters
Continue with exact representation converters
Choose a converter for the formats you are working with.