Number Base Converter (Binary, Hex, Octal, Decimal)
Convert numbers between binary, octal, decimal, hexadecimal, and any base from 2 to 36.
A number base is how many digits a system uses: decimal is base 10, binary base 2, octal base 8, and hexadecimal base 16. The same value looks different in each — decimal 255 is 11111111 in binary, 377 in octal, and FF in hex. Enter a value, pick the base it's in and the base you want, and this converter translates it exactly.
Results are estimates provided for general information.
Whole numbers only — no sign, decimal point, or 0x prefix. Letters aren't case-sensitive.
Hexadecimal (base 16)
FF
255 (decimal (base 10)) — converted exactly, at any length.
In every everyday base
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About the Number Base Converter
A number base — or radix — is simply how many distinct digits a counting system uses before it rolls over to another place. We count in base 10 (decimal) because we have ten fingers, using digits 0 through 9. Computers work in base 2 (binary), where every digit is a 0 or a 1, because that maps onto on-and-off electrical states. Base 16 (hexadecimal) is the programmer's shorthand for binary, using 0–9 then A–F, because each hex digit stands for exactly four binary digits, which makes long binary strings readable. Base 8 (octal) shows up in older systems and file permissions. The underlying value never changes — only its written form does — so the number two hundred and fifty-five is 255 in decimal, 11111111 in binary, 377 in octal, and FF in hexadecimal. This converter translates a whole number from any base to any other, covering the everyday bases 2, 8, 10, and 16 as well as any base from 2 to 36 (using letters for digits beyond 9). Enter a value, tell it which base the value is in and which base you want, and it does the conversion; when you convert from decimal it also shows the number in all four common bases at once. Digits are case-insensitive, and anything that isn't valid for the base you chose is flagged rather than quietly misread.
Frequently asked questions
How do you convert decimal to binary?+
Repeatedly divide the decimal number by 2 and record the remainders, then read them bottom to top. Decimal 255 becomes 11111111. This converter does it instantly — just set the 'from' base to decimal and the 'to' base to binary.
What is hexadecimal used for?+
Hexadecimal (base 16) is a compact way to write binary, since each hex digit equals four binary digits. Programmers use it for memory addresses, color codes (like #FF0000 for red), and byte values. It uses 0–9 then A–F for the values ten through fifteen.
Why is 255 equal to FF in hex?+
In hexadecimal, F is 15 and each place is worth 16 times the one to its right. So FF = 15 × 16 + 15 = 255. That's also why 255 is 11111111 in binary — eight ones, the largest value a single byte can hold.
What bases can this converter handle?+
Any base from 2 to 36. Below base 10 it uses a subset of the digits 0–9; above base 10 it uses letters A onward for the extra digit values, up to Z for 35. The common bases — binary, octal, decimal, and hexadecimal — are one tap away.
Are letters case-sensitive?+
No. You can enter hexadecimal or higher-base digits in upper or lower case — 'ff' and 'FF' are read the same. Output is shown in uppercase by convention. Any digit that isn't valid for the chosen base is flagged rather than misread.
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