Number Base Converter
Enter a number in binary, octal, decimal, or hexadecimal and instantly see it expressed in every other base. This free online developer calculator runs entirely in your browser — no signup, no data sent anywhere.
Inputs
Results
How It Works (Formula & Method)
The value you type is parsed from its input base into a standard integer, then re-formatted into each target base. Binary uses digits 0–1, octal 0–7, decimal 0–9, and hexadecimal 0–9 plus A–F. For example, hex FF parses to decimal 255, which is 11111111 in binary and 377 in octal.
Worked Example
Below is a worked example using the calculator's default values. The same numbers are pre-filled in the form above so you can press Calculate and see the result without typing anything.
Inputs used:
- Value: FF
- Input Base: 16
With these inputs, the calculator computes the metrics shown in the Results panel. Change any value and press Calculate again to see how the result responds — the live widget and the chart both update instantly.
About the Number Base Converter
Computers store every value as binary, but programmers read and write numbers in several bases depending on context: hexadecimal for memory addresses and color codes, octal for Unix file permissions, decimal for everyday math. Converting between them by hand is error-prone — this tool does it instantly and shows all four representations side by side.
Tips & Considerations
- Hex is popular because each digit maps to exactly four binary bits, so two hex digits represent one byte (0–255).
- Prefixes signal base in source code:
0xfor hex,0ofor octal,0bfor binary. Enter only the digits here — no prefix. - Hexadecimal is case-insensitive:
ffandFFare the same value.
Frequently Asked Questions
Why do programmers use hexadecimal?
Hex is compact and maps cleanly to binary — one hex digit equals four bits, so a byte is always exactly two hex digits. That makes memory addresses, color codes, and byte values far easier to read than long binary strings.
What is the largest number this handles?
JavaScript integers are reliable up to 2^53. Values larger than that may lose precision; for very large numbers use a dedicated big-integer tool.
Can I convert negative numbers?
Enter a leading minus sign with a decimal value. Binary, octal, and hex output here represents the magnitude — two’s-complement representation depends on the target word size.
What does the Number Base Converter compute?
The Number Base Converter takes 2 input values and returns 4 results. Convert numbers between binary, octal, decimal, and hexadecimal. Enter a value in any base and see all four representations at once.