Number Base Converter guide
Convert exact signed integers between positional number systems from base 2 through base 36.
What this tool does
Number Base Converter reads an integer according to a selected input radix and writes the same exact value in another radix. It supports binary, octal, decimal, hexadecimal, base 36, and every base between 2 and 36. Digits above 9 use letters A through Z without regard to input capitalization.
The conversion uses arbitrary-size integer arithmetic rather than floating-point numbers. Large values therefore remain exact instead of being rounded at JavaScript's normal safe-integer boundary. Inputs may contain a leading plus or minus sign. Spaces and underscores are ignored so grouped values such as 1111_0000 remain convenient to read.
When the matching base is selected, conventional 0b, 0o, and 0x prefixes are accepted for binary, octal, and hexadecimal input. The output is normalized to uppercase digits without grouping or a base prefix.
How to use it
- Enter the integer value.
- Set the input base from 2 through 36.
- Set the desired output base.
- Select Convert integer.
- Copy the exact normalized result or swap the bases for a reverse conversion.
The swap action uses the current output as the next input when a conversion result is available. This provides a quick round-trip check.
Benefits
- Supports every integer base from 2 through 36
- Uses exact arbitrary-size integer calculations
- Accepts signs, spacing, underscores, and matching common prefixes
- Identifies the first digit that is invalid for the selected base
- Performs all conversion locally without a network request
Scope and validation
This tool converts integers only. Decimal fractions, repeating fractions, exponents, two's-complement bit widths, IEEE 754 representations, and character encodings require different rules and are not accepted. A negative output uses a minus sign; it is not a signed fixed-width binary representation.
Input is limited to 4,096 digits to keep interaction responsive. Leading zeroes are removed from the normalized result because they do not change the mathematical integer. If an exact field width matters for a protocol, pad the result separately according to that protocol's specification.
If the octal value represents file access bits rather than a general integer, use the Unix Permission Calculator to see owner, group, other, and special-bit meanings. A numeric base conversion alone does not explain permission semantics.