How to convert hex to decimal, step by step

You need two things: the values of the sixteen hex digits, and the idea that each position is worth a power of 16. Everything else is multiplication and addition.

1. Know the digit values

Hexadecimal (base 16) uses sixteen symbols. 0–9 mean what they always mean; the letters A–F stand for 10–15:

Hexadecimal digits and their decimal and binary values
Hex	Decimal	Binary
0	0	0000
1	1	0001
2	2	0010
3	3	0011
4	4	0100
5	5	0101
6	6	0110
7	7	0111
8	8	1000
9	9	1001
A	10	1010
B	11	1011
C	12	1100
D	13	1101
E	14	1110
F	15	1111

2. Multiply each digit by its positional value

Positions count from the right, starting at 0. A digit at position n is worth digit × 16ⁿ. Take 0x2F3:

2×16² + F(15)×16¹ + 3×16⁰

= 2×256 + 15×16 + 3×1

= 512 + 240 + 3 = 755

So 0x2F3 = 755 in decimal.

3. A byte-sized example: 0xFF

F(15)×16¹ + F(15)×16⁰ = 240 + 15 = 255

0xFF = 255 — the largest value of one byte. Worth memorizing: it shows up constantly in masks, color channels and limits.

Decimal to hex: divide by 16

The reverse direction uses repeated division. Divide by 16, note the remainder, repeat with the quotient until you reach 0, then read the remainders bottom-up. Converting 755:

755 ÷ 16 = 47, remainder 3
47 ÷ 16 = 2, remainder 15 → F
2 ÷ 16 = 0, remainder 2

Read up: 2, F, 3 → 0x2F3

Common mistakes

Forgetting letters are values. A is ten, not "a". 0xA0 is 160, not 100.
Counting positions from the left. Powers grow from the right: the last digit is 16⁰.
Misreading case. 0xff and 0xFF are the same number; case carries no meaning.
Reading remainders top-down. In decimal → hex, the last remainder is the first digit.

Check yourself with the converter

Our hex to decimal converter shows this exact breakdown for any number you type — use it to verify your hand conversions while you practice. When the numbers live in binary too, the hex to binary converter shows the nibble mapping.