Hexadecimal to decimal
FF in base 16 is 15 × 16 + 15 = 255 in decimal. Its binary representation is 11111111.
Convert an integer between bases
Use up to 1,000 digits. A–Z represent values 10–35. Uppercase and lowercase are accepted; omit 0x, 0b, spaces, and separators.
Results
Base 10 result
255
| Base | Representation |
|---|---|
| Decimal (10) | 255 |
| Binary (2) | 11111111 |
| Octal (8) | 377 |
| Hexadecimal (16) | FF |
Magnitude bit length: 8. Signed values use a minus sign, not a fixed-width two’s complement encoding. Zero is represented by one binary digit.
Calculations and exports run locally in your browser. Your entries are not sent to a calculation service.
How to use the Number Base Converter
- 01
Enter an integer without prefixes, commas, or spaces, then choose its source base.
- 02
Choose the destination base and check the common-base table.
- 03
Use the result-and-reverse button to convert back, or copy and download the full conversion.
Examples
A binary place value
101101 in base 2 represents 32 + 8 + 4 + 1 = 45 in decimal, or 2D in hexadecimal.
Beyond ordinary safe integers
9007199254740993 remains exact when converted because the parser accumulates a BigInt. It is not first rounded into a JavaScript Number.
Read digits by place value
Each position contributes its digit value multiplied by a power of the base. The rightmost position has power zero. In base 16, letters A through F represent digit values 10 through 15; bases up to 36 extend that alphabet through Z.
Validate against the selected base
A digit must be smaller than the base. The input 102 is therefore invalid in binary even though it looks like a valid decimal integer. Uppercase and lowercase letters are accepted, and output letters are uppercase.
Signed integers are not bit patterns
A negative value is shown with a leading minus sign. The tool does not choose a fixed width, infer endianness, or generate two’s complement encodings. Magnitude bit length describes the absolute value’s binary digit count, with one digit used for zero.
What to know
- Integer conversion only, using bases 2–36 and a maximum of 1,000 input digits.
- No automatic radix prefixes, fixed-width machine encodings, separators, or fractional expansion.
Common questions
Should I include 0x or 0b?
No. Choose the base in the selector and enter only the signed digits. Prefixes are not automatically recognized; their letters can be ordinary digits in larger bases.
Can I convert a fraction such as 0.1?
No. This converter handles integers only. Fractional base expansions need additional precision and rounding choices that are outside this workflow.
Is there a maximum integer size?
The input is limited to 1,000 digits to keep parsing and rendering responsive. The output may contain more digits when converting to a smaller base.