Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal — or any base from 2 to 36 — with exact results for very long numbers.
Result
Enter your values and select Calculate to see the result.
How to use this calculator
- Enter a whole number and choose the base it is written in.
- The result shows it in binary, octal, decimal and hexadecimal. Enter another base in the last box for an extra conversion.
- Prefixes such as
0x(hex),0b(binary) and0o(octal) are accepted. Letters A–Z represent digit values 10–35.
Formula
A number in base b with digits dₙ…d₁d₀ has the value dₙ × bⁿ + … + d₁ × b + d₀.
To convert to another base, the value is repeatedly divided by the new base and the remainders are read in reverse order. Arbitrary-precision integers keep every digit exact.
Worked example
255 in other bases
255 = 15 × 16 + 15, so in hexadecimal it is FF. In binary it is 1111 1111 and in octal 377.
Hex to decimal
1A3 in base 16 = 1 × 256 + 10 × 16 + 3 = 419.
Assumptions and limitations
- Whole numbers only; fractional parts are not converted.
- Negative numbers are shown with a minus sign, not in two’s complement form.
- Input is limited to 256 digits.
Frequently asked questions
Why do programmers use hexadecimal?
Each hex digit represents exactly four binary digits, so long binary values such as colours (#FF8800) and memory addresses are much shorter to write.
What is the largest base supported?
Base 36, which uses the digits 0–9 and all 26 letters.