Hex Reference Tables

What is here

These are full tables, not samples — every value from 00 to FF, plus the complete 128-code ASCII set. The headers stay fixed while you scroll, so you never lose track of which column you are reading.

If you only memorise one thing, make it the sixteen digit values. Every table on this site is built from them, and knowing them turns most two-digit conversions into mental arithmetic.

Which table you want

All five cover the same 256 values; they differ in which column you need beside the hex.

• Reading a number. The decimal table answers “how much is this” — sizes, offsets, error codes, anything you need as a quantity.
• Reading bits. The binary table answers “which bits are set” — masks, flags, register contents, anything where individual bits carry meaning.
• Reading characters. The ASCII table answers “what does this byte say” — strings inside dumps, protocol keywords, escape codes.
• Reading permissions. The octal table is mostly for Unix file modes, where the underlying fields are three bits wide.
• All four at once. The hexadecimal table puts every base side by side, which is what you want when you are still building the intuition.

Why 00 to FF and no further

Because FF is one byte, and a byte is the unit everything else is built from. Two hex digits, eight bits, 256 values. Every longer value — a 32-bit address, a UUID, a SHA-256 hash — is just more bytes, and each pair of digits obeys exactly the rules in these tables.

That is the practical reason to learn one byte properly rather than skim a longer chart: the knowledge scales without any extra memorisation.

Using a table well

A lookup table is faster than a converter for a single small value and slower for everything else. Use these to check your own arithmetic, to spot a landmark value such as 7F or 80, and to build recall. For anything longer than two digits, the converter is exact at any length and will not slip a row.

Every table