Number base converter
Convert large integers exactly between binary, octal, decimal, hexadecimal and other bases.
- 1Add input
- 2Adjust settings
- 3Get your result
Tool input and files are processed in this browser without being uploaded.
Before you start
Convert a large signed integer between bases 2–36 without losing digits. Choose a common base pair or select both bases, then copy the exact result.
How to use this tool
- Choose a common conversion or set the input and output bases from 2 to 36.
- Enter one integer in the selected input base. For example, use 0xff with input base 16.
- Select “Convert number base”, check the labeled result, then copy its digits or download them.
Supported inputs and limits
One integer at a time, up to 4,096 input characters including sign, prefix and separators. The converted value can be longer.
Only whole numbers are supported. Matching 0b, 0o and 0x prefixes and single underscores between digits are accepted; other punctuation, internal spaces and fractions are rejected. Surrounding whitespace is trimmed.
Output digits a–z are lowercase. Leading zeros, prefixes and a negative sign on zero are not preserved. Negative values use a mathematical minus sign, not a fixed-width two's-complement bit pattern.
Worked example
Example input
9007199254740993
Example options
{
"from": 10,
"to": 16
}Example output
20000000000001
When something does not work
If conversion fails, check that every digit belongs to the chosen input base and that any 0b, 0o or 0x prefix matches it. Remove spaces and keep the input within 4,096 characters; a failed run clears the earlier result.
Frequently asked questions
Is a very large integer rounded?
No. Conversion uses BigInt integer arithmetic rather than a floating-point Number. It preserves the integer value exactly within the 4,096-character input limit.
Can I convert a negative binary register value?
A leading minus sign is treated as an ordinary negative integer. This tool does not interpret two's-complement, byte order or a chosen bit width; those need a separate encoding decision.
Documentation & further reading
Related tools
Unit converter
Convert length, area, mass, volume and temperature with compatible units side by side.
Percentage calculator
Find a share, calculate an amount from a percent, or measure percentage change.
Aspect ratio calculator
Reduce a width and height to a ratio, then plan a proportional pixel size.
Data size converter
Convert bit and byte amounts across decimal MB/GB and binary MiB/GiB units.