Convert Hexadecimal to Decimal Quickly
You see 0x1A3F in code and need the plain number. Hexadecimal looks confusing with its letters, but converting it is simple.
Quick Answer
Multiply each hex digit by its power of 16 and add them up. Or use the free converter at dotsapps.com to get the decimal value instantly.
What Hexadecimal Means and Why It Is Used
Hexadecimal (hex) is base-16. It uses digits 0-9 and letters A-F. A=10, B=11, C=12, D=13, E=14, F=15.
Programmers love hex because it is compact. One hex digit represents exactly 4 binary digits. So a byte (8 bits) is always exactly 2 hex digits.
You see hex in color codes (#FF5733), memory addresses (0x7FFF), MAC addresses, and error codes. Knowing how to read it is a core skill.
How to Convert Hex to Decimal by Hand
Let's convert 1A3F to decimal.
- Write each digit with its position power (right to left: 16⁰, 16¹, 16², 16³)
- Replace letters with numbers (A=10)
- Multiply and add
- 1 × 16³ = 1 × 4096 = 4096
- A × 16² = 10 × 256 = 2560
- 3 × 16¹ = 3 × 16 = 48
- F × 16⁰ = 15 × 1 = 15
4096 + 2560 + 48 + 15 = 6719
So 0x1A3F = 6719 in decimal.
Hex to Decimal for Color Codes
CSS color codes like #FF5733 are three hex values stuck together. Split them into pairs: FF, 57, 33.
- FF = 255 (red)
- 57 = 87 (green)
- 33 = 51 (blue)
This is how your browser turns a hex color code into the RGB values it needs to display the color on screen.
Quick Reference: Common Hex to Decimal Values
Keep these handy:
- 0x0A = 10
- 0x10 = 16
- 0x64 = 100
- 0xFF = 255
- 0x100 = 256
- 0x3E8 = 1000
- 0xFFFF = 65535
Notice that 0xFF = 255 and 0xFFFF = 65535. These are maximum values for 1-byte and 2-byte numbers. They come up constantly in programming.
How to Do It: Step-by-Step
- 1
Open the Number Base Converter at dotsapps.com
- 2
Select Hexadecimal (base 16) as the input
- 3
Type your hex number (like 1A3F or FF)
- 4
See the decimal value appear instantly
- 5
Copy the result or check binary and octal too
Frequently Asked Questions
What is 0xFF in decimal?
0xFF equals 255 in decimal. It is the largest value that fits in one byte (8 bits). That is why colors range from 0 to 255.
Why does hex use letters A through F?
Base-16 needs 16 symbols. We only have 10 number digits (0-9), so hex borrows the first six letters. A=10, B=11, C=12, D=13, E=14, F=15.
What does 0x mean before a hex number?
The 0x prefix tells the computer this is a hexadecimal number, not a decimal one. Without it, the number 10 could mean ten (decimal) or sixteen (hex).
How do I convert decimal to hex?
Divide the decimal number by 16 repeatedly. Write down each remainder. Replace remainders 10-15 with A-F. Read from bottom to top.
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