Hex to Decimal

A designer sends you the colour #FF5733 and asks what that looks like as ordinary RGB numbers. Hexadecimal is exactly this kind of shorthand — compact for anyone working with bytes, opaque to everyone else until you convert it.

Hex is base 16, read the same way you read decimal

A decimal number like 47 means four tens plus seven ones. Hexadecimal works the same way, except each position is worth a power of 16 instead of a power of 10, and a single digit can run from 0 up to 15 — which is why the letters A through F stand in for 10 through 15.

Take the hex value 2F. The 2 sits in the sixteens place and the F sits in the ones place, so the conversion is (2 × 16) + 15 = 47. Longer hex numbers just add more powers of 16 further to the left, the same way thousands and hundreds stack up in decimal.

Every hex digit and its decimal value

Colour codes are three decimal numbers in disguise

A colour code such as #FF5733 packs three bytes into six hex digits — two digits per channel, one channel each for red, green and blue. FF is 255, 57 is (5 × 16) + 7 = 87, and 33 is (3 × 16) + 3 = 51, giving RGB(255, 87, 51), a warm orange-red.

#FFFFFF converts to RGB(255, 255, 255) because every channel is at its maximum, which is why it renders as white. #000000 is black for the same reason in reverse — every channel sitting at zero.

Converting hex to decimal by hand

1. Write down each hex digit with its position, counting from the right starting at position 0.
2. Convert any letter digits — A through F — to their decimal values, 10 through 15.
3. Multiply each digit by 16 raised to its position.
4. Add the results together to get the final decimal number.
5. Sanity check: any two-digit hex value from 00 to FF should land somewhere between 0 and 255.

Hex to decimal questions