What the letters mean
Hexadecimal counts to 15 in a single place, using A to F for the values ten to fifteen.
The places are worth 1, 16, 256 and so on. So 2A means 2 x 16 + 10, which is 42.
Worked example
FF3A in hexadecimal is 65,338 in decimal. F is 15, so the calculation is 15 x 4096 + 15 x 256 + 3 x 16 + 10.
The same number in binary is 1111111100111010 and in octal it is 177472.
Where hex is used
Colours on the web are written as six hex digits, so #FF3A00 means 255 red, 58 green and 0 blue.
Memory addresses and byte values are usually written in hex because two digits describe one byte exactly.
Inputs for the hex calculator
Hexadecimal digits
Use 0 to 9 and A to F, in either case. Up to 13 digits stay exact.
CALCULATOR QUESTIONS
Hex calculator questions
What is FF in decimal?
255. Each F is 15, so 15 x 16 + 15 = 255.
What is 2A in decimal?
42, because 2 x 16 is 32 and A is 10.
Is hex case sensitive?
No. ff3a and FF3A are the same number, and the answer is shown in capitals.
Why does hex suit computers?
One hex digit is exactly four binary digits, so two hex digits describe one byte without any wasted bits.