Binary to Decimal Converter
Type a binary number made of 0s and 1s and get its decimal value right away. You can switch the bases if you need another conversion.
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The formula
Decimal = sum of (digit x 2^position), counting positions from 0 on the right.
How binary to decimal works
Each binary digit is worth a power of two, doubling as you move left: 1, 2, 4, 8, 16 and so on. Add up the values of the places that hold a 1.
For 1011, working from the right: 1 x 1 + 1 x 2 + 0 x 4 + 1 x 8 = 11.
A longer example
11010110 = 128 + 64 + 16 + 4 + 2 = 214. A handy trick is to write the powers of two above the digits and tick off the ones.
Why computers use binary
A circuit is either on or off, so two states are easy to build reliably. Everything a computer stores, from text to photos, is a long string of those 0s and 1s. Eight of them make a byte, which can hold a value from 0 to 255.
Examples to check
Type these into the calculator above to see how it behaves. Every result below was produced by the same calculator code that runs on this page.
| What you enter | What you get |
|---|---|
| Value: 1011; Binary (2); Decimal (10) | Base 10: 11 |
| Value: 11111111; Binary (2); Decimal (10) | Base 10: 255 |
| Value: 100000; Binary (2); Decimal (10) | Base 10: 32 |
| Value: 11010110; Binary (2); Decimal (10) | Base 10: 214 |
Binary to Decimal Converter: frequently asked questions
What is the largest number I can convert?
There is no practical limit. The converter uses big-integer arithmetic, so even hundreds of digits are fine.
Does it accept a 0b prefix?
Yes. A leading 0b is ignored.
How accurate is this calculator?
It uses standard double-precision arithmetic, accurate to about 15 significant digits. Results are rounded only for display.
Is what I enter in this calculator saved or sent anywhere?
No. The calculation runs in your browser, so what you enter is not sent to our servers. We only count, anonymously, whether a tool ran successfully.
Is this calculator free to use?
Yes. It is free, needs no sign-up and has no usage limit.
Last reviewed: October 3, 2026