How to use it
- Type or paste a binary number (0b prefix optional).
- Read the decimal result.
- Follow the place value table to see the working.
- Copy the result or switch to decimal to binary.
How to convert binary to decimal
Each binary digit (bit) is worth a power of 2, starting from 2⁰ = 1 on the right. Multiply each bit by its place value and add the results.
Example: 101101₂
| Bit | 1 | 0 | 1 | 1 | 0 | 1 |
|---|---|---|---|---|---|---|
| Place value | 32 | 16 | 8 | 4 | 2 | 1 |
32 + 8 + 4 + 1 = 45
The converter shows the same table for your number, grays out the zero bits and writes the final sum. It handles numbers of any length exactly, so a 64-bit value converts without rounding. Spaces and underscores in the input are ignored, which makes long numbers easier to paste.
Quick check: an 8-bit byte goes from 00000000 (0) to 11111111 (255), and a binary number ending in 0 is always even. For other bases, see binary to hex or the number base converter.
Frequently asked questions
What is 1010 in decimal?
8 + 2 = 10.
What is 11111111 in decimal?
255, the largest value of one byte.
Does it accept the 0b prefix?
Yes. 0b101101 and 101101 give the same result.
Last updated: November 12, 2026