Math & science
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal representations.
Interactive calculator
Convert between binary, octal, decimal, and hex
Enter a number in one base and instantly see its representation in the other common computer-number systems.
Results
Binary
11111111
Octal
377
Decimal
255
Hexadecimal
FF
How to use it
- 01Enter the value you want to convert.
- 02Choose the base the input value is currently written in.
- 03Read the binary, octal, decimal, and hexadecimal forms together.
Result guide
- The input must match the selected base or the conversion is invalid.
- Hexadecimal output is shown in uppercase for readability.
- This launch version focuses on whole-number conversion rather than fractions or signed bit width rules.
About this calculator
Number-base conversion pages are useful in computer science, electronics, and classroom math because learners often need to compare the same value across binary, octal, decimal, and hexadecimal.
A page that outputs all four major bases at once is more practical than forcing users to choose one narrow pair at a time.
Frequently asked questions
Why does the converter reject some inputs?
Because the characters entered do not belong to the selected base or do not form a valid value in that base.
Why show all four bases at once?
Because the same value is often compared across multiple bases in computer science and electronics problems.
Does this support negative or fractional values?
This launch version is focused on standard whole-number conversion across the four common bases.
Method and limitations
This calculator uses the formula and assumptions described on this page. We do not claim independent professional review. Direct references will be listed here when they support a specific rule or data source used by this calculator.
Results are estimates for general information. Verify current rules and assumptions before making financial, tax, or health decisions.
Read our Editorial and Verification Policy →Related calculators
Keep the next question one click away.
Roman Numeral Converter
Convert standard numbers to Roman numerals or convert valid Roman numerals back into numbers.
Exponent Calculator
Raise a base to any exponent and compare the result with the square and cube of the same base.
Logarithm Calculator
Calculate natural log, common log, and logarithm to a custom base for any positive value.