Hex to Decimal Converter

What the hex to decimal converter does

Hexadecimal, or hex for short, is the base-16 shorthand programmers use everywhere, and it is full of letters. This tool turns a hex value back into an ordinary decimal number. Type the hex in, press the button, and copy out the plain number.

It is what you reach for when you have a hex value in front of you, a colour code, a memory address, a byte from a hex dump, and you want to know the everyday number hiding behind it.

How to use it

1. Enter your hex number. Use the digits 0 to 9 and the letters A to F. Enter the letters as capitals.
2. Press Convert. The decimal value appears in the output box.
3. Click the result to copy it. Tap the output to send it to your clipboard.

Press Reset to clear both boxes.

Sixteen digits, which is where the letters come from

Here is the thing that puzzles people at first: why are there letters in a number? It comes down to counting. Decimal has ten digits, 0 through 9. Hex is base 16, so it needs sixteen single symbols, and we only have ten number digits. So once we pass 9, we borrow the first six letters of the alphabet to keep going. A is 10, B is 11, C is 12, D is 13, E is 14, and F is 15. They are not really letters here, they are digits wearing letter costumes. Each one stands for a single value from 10 to 15.

Place value: powers of sixteen

Hex is read exactly like any other number, by place value, only the columns are worth powers of sixteen. The rightmost column is the ones. The next one to the left is the sixteens. The next is the two hundred and fifty-sixes, which is sixteen times sixteen, and so on up. To read a hex number you multiply each digit by what its column is worth and add the results.

A worked example with real numbers

Take the hex number 2F.

• The 2 is in the sixteens column, so it is worth 2 × 16 = 32
• The F is in the ones column, and F means 15, so it is worth 15 × 1 = 15
• Add them: 32 + 15 = 47

So 2F in hex is 47 in decimal. One more worth memorizing: FF is 15 × 16 + 15 = 255, the largest value two hex digits can hold, which is exactly one byte.

Where you actually meet hex

Hex is not academic. It is the everyday language of a few corners of computing, and the reason is neat: sixteen is two to the fourth power, so one hex digit stands for exactly four binary bits. That makes hex a tidy, short way to write long binary.

You see it most in colours. A web colour like #FF0000 is three pairs of hex digits, one each for red, green, and blue. FF0000 is full red, no green, no blue. Run each pair through this converter and FF becomes 255, 00 becomes 0, which is the colour written as red 255, green 0, blue 0. You also meet hex in memory addresses, usually with a 0x in front to mark them as hex, because a long binary address shrinks to a short, readable hex one.

Questions people ask

Why does hex have letters in it?

Because base 16 needs sixteen single digits and we only have ten number symbols. The letters A to F fill in for the values 10 to 15, so each one is really just a digit.

Do I type the letters as capitals?

Yes, enter A to F as capitals. Uppercase is the usual convention for hex digits anyway.

What is FF in decimal?

255. Two F digits give 15 × 16 + 15 = 255, which is the most one byte can hold, so a byte runs from 00 to FF, or 0 to 255.

Why do programmers use hex instead of decimal?

Because one hex digit maps to exactly four binary bits, so hex is a short, readable stand-in for long binary. That makes colours, memory addresses, and raw bytes far easier to read than they would be in 0s and 1s.

References

1. Weisstein, Eric W. "Hexadecimal." From MathWorld, A Wolfram Resource. https://mathworld.wolfram.com/Hexadecimal.html