Free browser-based number converter
Binary to Decimal Converter
Convert binary numbers to decimal instantly. See the same value in hexadecimal and octal, inspect binary place values, or switch modes to convert decimal integers back to binary.
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How to convert binary to decimal
Binary is a base-2 number system, so each position represents a power of 2. Starting from the right, the place values are 1, 2, 4, 8, 16, 32, 64, and so on.
Multiply each binary digit by its place value and add the results. A digit of 0 contributes nothing; a digit of 1 contributes that power of 2.
Use the binary calculator
1
Enter a binary numberType a value using 0 and 1, such as 101101.
2
Read the conversionSee decimal, hexadecimal, octal, bit length, and parity.
3
Check the breakdownSee how each binary place value contributes to the answer.
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Binary to decimal example: 101101
The binary number 101101 has six digits. From left to right, they represent 2⁵, 2⁴, 2³, 2², 2¹, and 2⁰.
101101₂
= 1×2⁵ + 0×2⁴ + 1×2³ + 1×2² + 0×2¹ + 1×2⁰
= 32 + 0 + 8 + 4 + 0 + 1
= 45₁₀
So 101101 in binary equals 45 in decimal. The same value is 2D in hexadecimal and 55 in octal.
Binary, decimal, hex and octal table
| Decimal | Binary | Hex | Octal |
|---|
| 0 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 |
| 2 | 10 | 2 | 2 |
| 10 | 1010 | A | 12 |
| 15 | 1111 | F | 17 |
| 16 | 10000 | 10 | 20 |
| 45 | 101101 | 2D | 55 |
| 255 | 11111111 | FF | 377 |
| 256 | 100000000 | 100 | 400 |
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Binary to Decimal FAQ
How do you convert binary to decimal?
Multiply every binary digit by the corresponding power of 2, starting with 2⁰ on the right, then add the values.
What is 1010 in decimal?
Binary 1010 equals decimal 10 because 1×8 + 0×4 + 1×2 + 0×1 = 10.
What is 11111111 in decimal?
Binary 11111111 equals decimal 255. It is also FF in hexadecimal and 377 in octal.
Can I convert decimal back to binary?
Yes. Choose Decimal → Binary and enter a non-negative whole decimal number.
Can I enter spaces or underscores?
Yes. Spaces and underscores are ignored, and an optional 0b prefix is accepted.
Does it support very large numbers?
Yes. Integer conversions use JavaScript BigInt, although extremely large inputs are still limited by browser memory and performance.