How hex to decimal conversion works
Hexadecimal is base 16, using digits 0–9 and letters A–F for values 10–15. Each position is a power of 16 (1, 16, 256, … from the right). To convert, multiply each digit by its place value and add. For FF: F is 15, so 15×16 + 15×1 = 255. Hex is compact because two hex digits cover exactly one byte (0–255).
Longer values follow the same rule, just with more places. For 1A3: 1×256 + 10×16 + 3×1 = 256 + 160 + 3 = 419. A handy shortcut is to work left to right, multiplying the running total by 16 and adding the next digit - 1, then 26, then 419.
When you need something similar but not identical, the hex to RGB converter is there.
How to use this calculator
Enter a hex value using 0–9 and A–F. An optional 0x prefix and spaces are ignored. To reverse the conversion, use the decimal to hex calculator.
The conversion runs in your browser, so nothing you paste is uploaded or stored. Case makes no difference: ff, FF and 0xFF all return 255, and a trailing h from assembler dumps should be removed before pasting.
Once that is settled, the decimal to binary calculator takes care of the next part.
Hex to decimal reference table
Common conversions:
| Hex | Decimal |
|---|---|
| A | 10 |
| F | 15 |
| 10 | 16 |
| FF | 255 |
| 100 | 256 |
| FFFF | 65535 |
For binary instead, see the binary to decimal calculator.
Recognising these anchors saves time when reading raw data. A value that stops at FF is a single byte, FFFF is a 16-bit field such as a network port, and FFFFFFFF is a 32-bit integer or an IPv4 address in packed form.
Frequently asked questions
- What is FF in decimal?
- Hex FF equals decimal 255: 15×16 + 15 = 255, the highest value for one byte.
- What do A to F mean in hex?
- They are single-digit symbols for 10 through 15: A=10, B=11, C=12, D=13, E=14, F=15.
- Why is hex used in computing?
- Two hex digits map exactly to one byte (8 bits), making colors, memory addresses, and binary data shorter to read.
- Does the 0x prefix matter?
- No. 0x just signals that a number is hexadecimal. This tool ignores it, so FF and 0xFF both give 255.
- What is the largest hex value this handles accurately?
- Values up to 1FFFFFFFFFFFFF (about 9 quadrillion) convert exactly, because that is the largest whole number a browser can hold without rounding. Longer hex strings still return a result, but the last digits may be approximate.