Number Base Converter
Convert a number between any two bases from 2 to 36, with live results, fractional support and a step-by-step division table.
Base 10 → base 2
11111111
Conversion steps (integer part)
Divide the decimal integer part repeatedly by 2 and collect the remainders. Reading the remainders from the last row up gives the digits of the result.
| Division | Quotient | Remainder | Digit |
|---|---|---|---|
| 255 ÷ 2 | 127 | 1 | 1 |
| 127 ÷ 2 | 63 | 1 | 1 |
| 63 ÷ 2 | 31 | 1 | 1 |
| 31 ÷ 2 | 15 | 1 | 1 |
| 15 ÷ 2 | 7 | 1 | 1 |
| 7 ÷ 2 | 3 | 1 | 1 |
| 3 ÷ 2 | 1 | 1 | 1 |
| 1 ÷ 2 | 0 | 1 | 1 |
Runs entirely in your browser. Fractional parts are shown to 10 places and may be truncated if they repeat.
How it works
- Type or paste your number, including an optional fractional part after the radix point.
- Pick the source and target base from 2 to 36, or tap the binary, octal, decimal and hex chips.
- Read the live result, check the four common bases in the panel below, and copy the one you need.
Frequently asked questions
- How do letters work in bases above 10?
- Bases above 10 need more than ten digit symbols, so the letters a to z stand for the values 10 to 35. In hexadecimal, for example, the digit f equals 15. The converter accepts both uppercase and lowercase letters and flags any digit that is not valid in the base you selected.
- Can I convert fractional numbers like 10.101 in binary?
- Yes. Anything after the radix point is treated as a fractional part and converted to up to 10 places in the target base. Note that many fractions do not terminate in another base — decimal 0.1 becomes a repeating fraction in binary — so the result may be truncated at the tenth place.
- Is there a limit on how large the number can be?
- Integer parts are converted with arbitrary-precision big-integer arithmetic, so even numbers far beyond 64 bits convert exactly with no rounding. Fractional parts use standard floating-point math, which is accurate to roughly 15 significant decimal digits — more than enough for the 10 places shown.
- Does the converter send my numbers to a server?
- No. The entire conversion runs in JavaScript inside your browser, and the page makes no network requests with your input. Nothing you type is uploaded, logged or stored anywhere, so it is safe to use with serial numbers, keys or any other sensitive values.
- How is the division and remainder table calculated?
- The classic method for converting an integer to another base is repeated division: divide the number by the target base, record the remainder, and repeat with the quotient until it reaches zero. The remainders read from bottom to top are the digits of the result, and the table shows every one of those divisions.
About this tool
This number base converter translates values between any positional numeral system with a radix from 2 to 36. That covers the four bases programmers use daily — binary, octal, decimal and hexadecimal — plus every base in between and beyond, up to base 36, which uses all ten digits and all twenty-six letters. Whatever target base you choose, a results panel always shows your number in the four common bases at once, so you never need a second conversion to compare representations.
Everything happens client-side in your browser as you type: no submit button, no upload, no waiting. The integer part is parsed into an arbitrary-precision big integer, which means a 100-digit decimal number converts to binary exactly, with none of the rounding errors that calculators limited to 64-bit numbers produce. Fractional parts are converted by the standard multiply-and-take-the-integer method and shown to 10 places. Invalid digits — like a 9 in an octal number or a g in hex — are flagged immediately with a message telling you exactly which character is wrong.
Typical uses include reading hexadecimal color codes and memory addresses, converting binary permission masks and subnet values in networking, checking assembly or embedded-systems homework, and decoding base-36 identifiers such as short URL slugs. The swap button reverses the conversion direction in one tap, carrying the current result back into the input.
For learning, open the conversion steps panel: it lists the full division and remainder table used to convert the integer part into the target base, the same procedure taught in computer science courses. Following the remainders from the last division back to the first shows precisely where each digit of the result comes from.