Number Base Converter
Convert any number between bases 2 through 36 — binary, octal, decimal, hexadecimal and everything in between. Free, instant and private: all math happens right in your browser.
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How to use the number base converter
- Type your number. Enter the value in the box above — digits 0–9 and letters A–Z are allowed depending on the base, and you can include a minus sign and a fractional part like 1010.101.
- Pick the bases. Choose the base your number is written in ("From base") and the base you want ("To base"), anywhere from 2 to 36. Use the ⇆ button to swap directions.
- Copy the result. The conversion updates instantly as you type, together with a quick reference table showing your number in binary, octal, decimal and hex.
About this tool
This free base converter (also called a radix converter) translates numbers between any two positional numeral systems from base 2 to base 36. That covers all the systems programmers use daily — binary to decimal, decimal to hex, octal to binary — plus unusual ones like base 3, base 12 or base 36, which uses all ten digits and all twenty-six letters. It even converts fractional values such as 0.1 or FF.8, and because it uses arbitrary-precision integer math, whole numbers with hundreds of digits convert without any loss of accuracy.
Everything is computed locally in your browser with plain JavaScript — nothing is uploaded, logged or stored, and the tool keeps working offline once the page has loaded. Prefixes like 0x, 0b and 0o are recognized automatically when they match the selected source base, and spaces, commas and underscores used as digit separators are ignored.
Frequently asked questions
Which characters are valid digits in higher bases?
Bases above 10 use letters as extra digits: A stands for 10, B for 11, and so on up to Z for 35 in base 36. For example, in base 16 (hexadecimal) the valid digits are 0–9 and A–F. Letter case does not matter — ff and FF are the same hex number.
Can it convert fractions like 0.1 between bases?
Yes. The integer and fractional parts are converted separately using exact rational arithmetic. Some fractions terminate in one base but repeat forever in another — decimal 0.1 is the infinite binary fraction 0.000110011… — in which case the result is truncated to 20 fractional digits and a note appears.
How large can the numbers be?
Integers are converted with arbitrary-precision (BigInt) arithmetic, so numbers with thousands of digits convert exactly — there is no 53-bit floating-point limit like many other converters have. Inputs are capped at 10,000 characters simply to keep the page responsive.
What is base 36 used for?
Base 36 uses 0–9 plus A–Z, making it the most compact case-insensitive alphanumeric encoding. It is popular for short URLs, license keys, order references and database IDs because it packs large numbers into short, readable strings.