Base converter: binary, octal, decimal and hexadecimal
Convert numbers between binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16) and any base from 2 to 36, in both directions and instantly. Type into any field and the rest update on their own. Handles very large integers (arbitrary precision with BigInt). Everything runs in your browser: nothing is uploaded to any server.
How to convert between number bases
- Type or paste a number into the field for its base (for example, into “Decimal”).
- The other fields fill in instantly with the same value in each base.
- For another base, pick one from 2 to 36 in the “Custom base” selector.
- Click “Copy” next to any field to grab the result.
- If a digit is not valid for that base, the field turns red and warns you.
Frequently asked questions
How do I convert binary to decimal?
Type the binary number (only 0s and 1s) into the “Binary” field and the “Decimal” field will show its value instantly. It works the same in any direction: decimal to binary, hexadecimal to decimal, and so on.
What is a number base?
It is the number of distinct digits a system uses to represent numbers. Decimal (base 10) uses 0–9; binary (base 2) uses 0 and 1; hexadecimal (base 16) uses 0–9 and A–F. The same value is written differently in each base.
Which bases does it support?
The four common ones —binary (2), octal (8), decimal (10) and hexadecimal (16)— plus any custom base from 2 to 36. Beyond 10, the letters A–Z are used as extra digits (A=10, B=11… Z=35).
Does it work with very large numbers?
Yes. It uses BigInt, so it converts integers of arbitrary size without losing precision, unlike floating-point calculations that round off past a certain size.
Does it support negative and decimal numbers?
It supports negative integers (put a “-” sign in front). It does not convert the fractional part (after the decimal point); it works with whole numbers.
Is my number uploaded to any server?
No. All conversion happens in your browser with JavaScript. Nothing you type is sent over the internet, and it works offline.