Learn base 16
Hexadecimal Guides
How hexadecimal works, why it exists, and how to convert without a tool.
Where to start
If base 16 is new to you, read what hexadecimal is first, then what A to F mean. Between them they cover everything you need to read a hex value with confidence.
If you already know the basics and want to work without a converter, the by-hand tutorials have worked examples and practice problems with answers.
Three kinds of guide
- Foundations — what base 16 is, how place value works, and why the letters are there. Start here if hex still looks arbitrary.
- Comparisons — hex against decimal, binary and octal. These answer “why this notation and not that one”, which is usually the question underneath “what is hex”.
- Tutorials — converting by hand, with practice problems. The converters will always be faster; the point is to still be able to read a value when you are looking at a datasheet rather than a browser.
The one fact everything rests on
Sixteen is 24. One hex digit is therefore exactly four bits, one byte is exactly two hex digits, and a 32-bit register is exactly eight. No other readable base lines up with binary that cleanly, and almost every practical property of hex follows from it — why colors are six digits, why a MAC address is twelve, why you can convert hex to binary in your head but not hex to decimal.
If a guide here ever seems to be making a fuss about four bits, that is why.