How to convert hex to decimal by hand

This guide teaches the method, not just the answer. 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. If you only need a value right now, the converter gives it instantly and the 0x00–0xFF table covers every byte.

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:

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:

So 0x2F3 = 755 in decimal.

3. A byte-sized example: 0xFF

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:

Mental shortcuts for two-digit hex

Most hex you meet is one byte, two digits. Multiply the first digit by 16 and add the second, and the first few powers of 16 are worth memorizing:

Two more tricks: a byte ending in 0 is a multiple of 16, and a byte of Fs is one less than the next power of 16 (0xFF = 256 − 1, 0xFFF = 4 096 − 1).

Practice: five conversions to try

Work them on paper first, then open the answers.

1. 0x1F
2. 0x64
3. 0xC8
4. 0x3E8
5. 0xABC

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.