Integer Base Converter
Convert whole numbers between binary, octal, decimal, hexadecimal, and any custom base from 2 to 36.
Binary
11111111
Octal
377
Decimal
255
Hexadecimal
ff
Base 20 (custom)
cf
Recommended Settings
Pro Tips
- •For very large numbers, all math is done with BigInt so precision isn't lost the way it would be with regular JavaScript numbers
- •Letters a-z represent digit values 10-35 for bases above 10, following the standard convention used in most programming languages
- •The custom base slot lets you convert to any base from 2 up to 36, useful for less common encodings like base32 or base36
- •Invalid digits for the selected input base are flagged immediately, so a stray letter in a 'binary' value won't silently produce a wrong result
Most Popular
Most developers convert decimal to hexadecimal or binary, or the reverse when reading raw memory or flag values
When to Use This Tool
Turn a hexadecimal value from code or a debugger into decimal, or vice versa.
Convert a decimal permission or flag value into its binary or octal representation.
See exactly how the same quantity is represented across different number bases.
Convert a number into an unusual base like base36 for use in a short identifier.
How It Works
Parse the input value as a BigInt in the selected input base, digit by digit
Hold the result as a single arbitrary-precision decimal value internally
Convert that value into binary, octal, decimal, hexadecimal, and your chosen custom base by repeated division
100% Private
Files never leave your device. All processing happens locally in your browser.
Lightning Fast
Powered by Client-side BigInt arithmetic for optimal performance on modern browsers.
Open Source
Built with verified, open-source libraries. Fully transparent.
Frequently Asked Questions
Does this support negative numbers?
This tool works with non-negative whole numbers. For negative values, convert the absolute value and apply the sign separately.
Is there a limit to how large a number I can convert?
No practical limit - the tool uses BigInt arithmetic internally, so it correctly handles numbers far larger than JavaScript's standard 53-bit safe integer range.
What's the highest base supported?
Base 36, which uses all 10 digits plus all 26 letters of the alphabet - the highest base that can be represented with standard alphanumeric characters.
Is my data sent to a server?
No. All conversion happens locally in your browser using JavaScript.