Why does programming use hexadecimal instead of just decimal?

Hexadecimal maps cleanly onto binary — one hex digit represents exactly 4 bits — making it a compact, readable way to represent binary data like colors, memory addresses, and byte values.

What does hex FF equal in decimal?

255, which is also the maximum value a single 8-bit byte can hold — this is why FF appears so often in color codes and byte-related values.

What hex digits represent values above 9?

Letters A through F represent the values 10 through 15, extending the ten decimal digits (0-9) to a full set of sixteen hexadecimal digits.

Hex ↔ Decimal Converter

Convert between hexadecimal, decimal, binary, and octal. All four update simultaneously as you type.

Hexadecimal (Base 16)

Decimal (Base 10)

Binary (Base 2)

Octal (Base 8)

Batch Converter

Paste multiple numbers (one per line), select the input base, and convert all at once.

Input (one per line)

Input Base

Common Hex Reference

HEX	DEC	BIN	OCT	Notes
00	0	00000000	0	Zero / null
0F	15	00001111	17	Lower nibble
10	16	00010000	20
1F	31	00011111	37
20	32	00100000	40	Space (ASCII)
40	64	01000000	100	@ (ASCII)
7F	127	01111111	177	DEL (ASCII)
80	128	10000000	200	Sign bit (8-bit signed)
A0	160	10100000	240
C0	192	11000000	300	Common subnet mask byte
FF	255	11111111	377	Max byte / 8-bit unsigned
100	256	100000000	400
FFFF	65535	1111111111111111	177777	Max 16-bit unsigned

How to use

Type in any of the four fields (HEX, Decimal, Binary, Octal) — all others update instantly
If the hex value looks like a CSS color (#RRGGBB or RRGGBB), a color swatch preview appears
Use the Batch Converter to convert many numbers at once — paste one per line, select the base, and click Convert All
The reference table shows common hex values and their equivalents in all bases
Hex input is case-insensitive (A = a)

About this Hex to Decimal Converter

Hexadecimal (base 16) uses sixteen digits — 0 through 9, then A through F for values 10 through 15 — instead of the ten digits used in decimal (base 10). It's the standard way to represent color codes, memory addresses, and byte values because it maps cleanly onto binary.

Why hex maps neatly to binary

One hex digit represents exactly 4 binary bits (since 16 = 2⁴), so a full byte (8 bits) converts to exactly 2 hex digits. This clean relationship is why programmers use hex as a compact, human-readable shorthand for binary data instead of writing out long strings of 1s and 0s.

Worked example

Converting hex FF to decimal: F represents 15, and in the two-digit place, the value is (15 × 16) + 15 = 240 + 15 = 255. This is why FF appears constantly in web colors and byte values — it's the maximum value a single byte (8 bits) can hold.

Where hex shows up

CSS colors: #FF0000 is pure red, where each pair of hex digits represents red, green, and blue channel values from 0–255
Memory addresses and pointers in low-level programming and debugging
MAC addresses and some network identifiers
Character encoding references, like Unicode code points