Number System Converters

A number system, or base, is a way of writing numbers with a fixed set of digits. Everyday counting uses base 10. Computers store everything in base 2 (binary), and programmers shorten long binary strings with base 8 (octal) or base 16 (hexadecimal), where the letters A to F stand for the values 10 to 15.

The same two methods cover every conversion. To go from another base to decimal, multiply each digit by its place value (a power of the base) and add the results. To go from decimal to another base, divide by the base again and again and read the remainders from last to first. Binary, octal and hexadecimal convert to each other by grouping bits: three binary digits make one octal digit, and four make one hexadecimal digit.

If you want one tool for everything, use the base converter, which works between any two bases from 2 to 36. The single-purpose pages are quicker when you know what you need: binary to decimal, decimal to binary (including fractions, with the division steps), hex to decimal, decimal to hex, binary to hex, hex to binary and binary to octal. The hex converter handles ten conversion pairs between hexadecimal, decimal, binary and octal and shows its calculation steps.