This hex calculator converts between hexadecimal and decimal. Default mode is hex to decimal with value FF, which equals 255. Switch modes when you need the reverse direction.
Developers and students use it while reading color codes, memory dumps, and bit masks. For binary string work on the same theme, [INTERNAL LINK NEEDED: binary calculator]. For percent math beside coding homework, use the percentage calculator.
How the formula works
Hex to decimal parses the string in base 16. Decimal to hex formats a non-negative integer in base 16. Digits above 9 use letters A through F.
Worked example
FF hex means 15×16 + 15 = 255 decimal.
| Input | Value |
|---|---|
| Mode | Hex to decimal |
| Value | FF |
| Result | 255 |
How to use the fields
- Value is the hex string or decimal number depending on mode.
- Convert chooses hex to decimal or decimal to hex.
Place values
Each hex digit is a power of 16. Two digit values like FF sit in the 0 to 255 range common in byte sized RGB channels.
Common mistakes
- Leaving mode on hex to decimal while typing a decimal like 255 without letters
- Using letters beyond F
- Expecting signed two’s complement formatting from this simple converter
- Forgetting that 10 hex is 16 decimal, not ten
Color codes
Web colors often appear as six hex digits. Converting one channel such as FF helps you see the 0 to 255 intensity before you edit CSS by hand.
Classroom practice
Convert FF to 255, then convert 255 back to hex and confirm FF. Round trips catch mode mistakes immediately.
Ask what 10 hex equals in decimal. Students who answer 10 are mixing bases; the correct decimal value is 16.
Debugging habit
When a dump shows 0xFF, write 255 beside it in notes so magnitude is obvious during reviews.
Bytes and words
Two hex digits make one byte in the 00 to FF range. Four hex digits often represent 16 bit values. Knowing those widths helps when a dump pads with leading zeros.
This converter returns the numeric value without forcing a fixed width display.
Case and prefixes
Languages may show 0xFF or hFF style prefixes. Strip prefixes before entry if the field expects bare hex digits.
Uppercase and lowercase letters are equal in value. Pick one style for team docs and stay consistent.
Mental math shortcuts
F hex is 15. A hex is 10. Memorizing A through F speeds reading without the calculator. Still verify critical addresses with the tool.
Powers of two often land on round hex boundaries, which is why memory sizes look tidy in hex dumps.
ASCII and character codes
Some lessons connect byte values to characters. Hex 41 is decimal 65, a common example for uppercase A in ASCII. Convert with the tool, then look up the character table separately.
Not every byte is a printable character. Use conversion for the number first, then interpret meaning in context.
When a protocol doc writes multi byte fields, convert each byte or the whole width as the doc specifies. Mixing those approaches creates off by byte errors.
Endianness reminder
Multi byte hex values may be written with the most significant byte first or last depending on the system. Conversion of a single value like FF is unaffected, but longer strings need an endianness rule from the spec you are reading.
When unsure, convert byte by byte in the order the protocol diagram shows.
Document the endianness beside any converted address so the next reader does not reverse the bytes again.
Nibble view
Each hex digit is a nibble of four bits. FF is two nibbles making eight bits. Thinking in nibbles makes binary translation faster when you need it.
You can convert FF to binary 11111111 by expanding each F as 1111, which reinforces why hex shorthand exists.
Limitations
No bitwise operators, no floating hex formats, and no automatic bit width padding beyond what you type.