Base Converter
Input base
11111111377255ffA number base converter for binary to decimal, decimal to binary, hex to decimal, decimal to hex, and more. Enter a number in binary, octal, decimal, or hexadecimal and see it instantly converted into all four bases at once. It supports arbitrarily large integers (using exact integer math, not floating point) and negative numbers with a leading minus sign.
Frequently asked questions
Why does my input show as invalid?
Each base only allows certain digits — binary allows just 0 and 1, octal allows 0-7, and hexadecimal allows 0-9 plus a-f. If your input contains a character outside that set for the selected input base, it can't be parsed.
Is there a limit to how large a number I can convert?
No practical limit — conversion uses arbitrary-precision integer arithmetic, so very large numbers (far beyond what a 64-bit integer can hold) convert exactly, without rounding errors.
How do I convert binary to decimal?
Enter the binary number with binary selected as the input base and the decimal value appears alongside it. Each binary digit is a power of two, so 1011 is 8 + 0 + 2 + 1 = 11.
How do I convert hex to decimal or decimal to hex?
Set the input base to hexadecimal and type a value like FF to see 255 in decimal, or choose decimal and type 255 to see FF in hex. The hex letters A to F stand for the values 10 to 15, and upper or lower case both work.
How do I convert binary to hex?
Enter the binary number and read the hexadecimal row. Every 4 binary digits map to one hex digit, so 11110000 becomes F0.