Binary Calculator
Binary to decimal, hex and octal, with validation that works.
Work out Binary. Binary to decimal, hex and octal, with validation that works. Exact where exactness is possible.
Decimal
255
8 bits
Every base writes the same quantity differently — 255 is 11111111 in binary and FF in hex, and none is more correct than the others. Hexadecimal earns its place in computing because one hex digit is exactly four binary digits, so conversion between them needs no arithmetic at all.
How the Binary Calculator works
Binary to decimal, hexadecimal and octal. The validation is stricter than it looks: the standard parsing routine silently stops at the first invalid character, so '1234' would read as valid binary. This verifies the whole string round-trips before accepting it.
Also known as: binary to decimal · decimal to binary converter · binary converter · binary to hex converter
Frequently asked questions
How do I convert binary to decimal?
Add the place values where a 1 appears — 1, 2, 4, 8 and so on. 11111111 is 255, which is every bit set in a byte.
How many values fit in 8 bits?
256, from 0 to 255. Each extra bit doubles the range.
Why does computing use hexadecimal?
Because one hex digit is exactly four binary digits, so conversion between them needs no arithmetic at all — you can read hex off binary in blocks of four.
What is the largest number here?
Whatever fits in an exact integer, about 9 quadrillion. Beyond that, values lose precision and would be displayed wrongly, so they are refused.
Put this calculator on your own site
Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.
<iframe src="https://www.thecalclibrary.com/embed/binary-calculator" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px" loading="lazy" title="Binary Calculator"></iframe>The only condition is that the credit line stays visible. It sits inside the frame, so you do not have to do anything to keep it.