How to use the Binary to Decimal Converter
- Type or paste the binary number into the first box.
- Read the decimal result in the second box, and click Copy to copy it.
- Scroll to How it works for the step-by-step method.
How to convert binary to decimal
Each binary digit (bit) is worth a power of 2, starting with 2⁰ = 1 on the right: 1, 2, 4, 8, 16, 32, 64, 128 and so on. Add up the values of the positions that hold a 1.
Example: 101101 = 32 + 0 + 8 + 4 + 0 + 1 = 45.
A quick way for long numbers: start with 0, and for each bit from left to right, double your total and add the bit. For 101101: 1 → 2 → 5 → 11 → 22 → 45.
Reference table
| Decimal | Binary | Hex | Octal |
|---|---|---|---|
| 0 | 0000 | 0 | 0 |
| 1 | 0001 | 1 | 1 |
| 2 | 0010 | 2 | 2 |
| 3 | 0011 | 3 | 3 |
| 4 | 0100 | 4 | 4 |
| 5 | 0101 | 5 | 5 |
| 6 | 0110 | 6 | 6 |
| 7 | 0111 | 7 | 7 |
| 8 | 1000 | 8 | 10 |
| 9 | 1001 | 9 | 11 |
| 10 | 1010 | A | 12 |
| 11 | 1011 | B | 13 |
| 12 | 1100 | C | 14 |
| 13 | 1101 | D | 15 |
| 14 | 1110 | E | 16 |
| 15 | 1111 | F | 17 |
Frequently asked questions
What is 1111 in decimal?
15. Four 1s are 8 + 4 + 2 + 1. In general, n ones in a row equal 2ⁿ − 1, so 11111111 is 255.
What is 1010 in decimal?
10: 8 + 0 + 2 + 0.
How do I read negative binary numbers?
Computers usually use two's complement. Tick Signed (two's complement) and choose the bit width: in 8 bits, 11111111 is −1.