Hex to Decimal

Part of the Fundamentals section of Coddy's Assembly journey — lesson 11 of 45.

Hexadecimal (base 16) works the same way as binary and decimal — each position has a place value. In hex, each position is a power of 16.

Place values in hex:

Hex digit values to remember:

Example 1: Convert 0x2A to decimal

Position	Hex digit	Place value	Calculation
Left	2	16	2 × 16 = 32
Right	A (10)	1	10 × 1 = 10
Total			32 + 10 = 42

So 0x2A = 42 in decimal.

Example 2: Convert 0xFF to decimal

Position	Hex digit	Place value	Calculation
Left	F (15)	16	15 × 16 = 240
Right	F (15)	1	15 × 1 = 15
Total			240 + 15 = 255

So 0xFF = 255 in decimal.

Example 3: Convert 0x3E8 to decimal

Position	Hex digit	Place value	Calculation
Left	3	256	3 × 256 = 768
Middle	E (14)	16	14 × 16 = 224
Right	8	1	8 × 1 = 8
Total			768 + 224 + 8 = 1000

So 0x3E8 = 1000 in decimal.

The formula:

For a hex number with digits ... d₂ d₁ d₀:

Value = (... + d₂ × 16² + d₁ × 16¹ + d₀ × 16⁰)

Try it yourself

This lesson doesn't include a code challenge.

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1The Machine

4Data Definition

7Hello World

2Number Systems

5Exit Syscall

3First instruction - MOV

6Write Syscall