Hex Calculator · Practical guide
What Is FF in Decimal?
FF in hex is 255 in decimal and 11111111 in binary — the maximum value of a single byte.
At a glance
The short answer
FF in hexadecimal equals 255 in decimal and 11111111 in binary. Each F is worth 15: the right F contributes 15 × 1 = 15, and the left F contributes 15 × 16 = 240. Adding them: 240 + 15 = 255. This makes 0xFF the largest value one byte (8 bits) can hold, which is why it shows up constantly in programming.
Interactive tool
Hex Calculator
Enter your own values, then compare the result with the examples below.
Result
Common hex-to-decimal lookups
| Hex | Decimal | Binary |
|---|---|---|
| A | 10 | 1010 |
| F | 15 | 1111 |
| 10 | 16 | 10000 |
| FF | 255 | 11111111 |
| 100 | 256 | 100000000 |
| FFFF | 65,535 | 1111111111111111 |
Why FF matters
One byte holds 8 bits, and 8 bits can represent 2⁸ = 256 distinct values, from 0 to 255. That ceiling is 0xFF. You see it in RGB color codes (the color #FF5733 has its red channel at the full 255, and the whole code equals decimal 16,734,003), in subnet masks (255.255.255.0 is FF.FF.FF.00), and anywhere raw bytes are displayed.
Convert or compute with FF yourself
To see FF in decimal with the calculator above, enter FF as the first number, choose addition, and enter 0 as the second number. The result panel shows the hex value, its decimal equivalent 255, and the binary form 11111111, plus the arithmetic steps. The same trick converts any hex value up to FFFF (65,535) and beyond.
Frequently Asked Questions
What is FFFF in decimal?
FFFF in hex equals 65,535 in decimal. That is the maximum value of an unsigned 16-bit integer, which is why 65535 appears as a limit in many older systems and file formats.
What is FF in binary?
FF equals 11111111 in binary — eight 1s. Each hex digit is exactly four bits, and F (15) is 1111, so FF is two groups of 1111.
Why is 255 such a common maximum in computing?
Because one byte (8 bits) holds values 0 through 255, and 255 in hex is the tidy value FF. Byte-based limits, from color channels to IP octets, all top out at 255.
How do I convert hex to decimal without a calculator?
Multiply each digit by its power of 16 and add. For FF: 15 × 16 + 15 × 1 = 240 + 15 = 255. For longer values, work left to right doubling by 16s.