Convert numbers between binary, octal, decimal and hexadecimal.
Converted locally in your browser.
How do you convert a number between binary, decimal and hexadecimal?
A number base converter parses the value from its input base into an integer, then formats it into base 2, 8, 10 and 16 all at once. Only digits valid for the chosen base are accepted. For example, the hex value FF equals 255 in decimal, 11111111 in binary and 377 in octal. This lets developers see every representation instantly.
Understanding your result
Only digits valid for the chosen base are accepted (for example, 2 is not valid binary).
Formula and method
The value is parsed from its input base into an integer, then formatted into base 2, 8, 10 and 16.
Assumptions and limitations
The tool converts whole integers between bases and only accepts digits valid for the chosen input base. It does not handle fractional numbers, negative values, or non-integer notation, and it works on the value's magnitude rather than any two's-complement representation used inside a specific data type.
Worked example
The hex value FF equals 255 in decimal, 11111111 in binary and 377 in octal.
How to use this tool
- Enter the value.
- Choose the input base.
- Read all four representations.
Common mistakes to avoid
- Entering hex letters while the input base is set to decimal.
About the Number Base Converter
Convert a number from one base to binary, octal, decimal and hexadecimal all at once.
Who should use this tool
Programmers working with bitmasks and flags, embedded developers reading hardware registers, and students learning number systems. Anyone who needs to see a value in binary, octal, decimal, and hexadecimal at once — for example checking a permission bitfield or a hex colour byte.
Benefits
- Shows binary, octal, decimal and hex simultaneously
- Rejects digits invalid for the selected base
- Ideal for inspecting bitmasks and register values
- Converts locally with no data leaving the browser
Practical use cases
- Reading a hardware register value written in hex
- Checking a permission bitmask in binary
- Converting a hex colour byte to decimal
- Teaching or learning how number bases relate
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Frequently asked questions
Does it handle large numbers?
It handles standard integers reliably; extremely large values may lose precision.
Why is a digit like 2 rejected when I choose binary?
Binary uses only the digits 0 and 1, so any other digit is invalid input for base 2. Each base allows a fixed set of digits: octal permits 0 to 7, decimal 0 to 9, and hexadecimal 0 to 9 plus A to F. The tool blocks digits outside the chosen base.
Can it convert negative or fractional numbers?
No. This converter works with non-negative whole integers only. It does not accept a minus sign, decimal point, or fractional part, and it does not model two's-complement bit patterns for a specific integer width. For those cases you need a calculator built for signed or fixed-point representations.