Binary to Decimal Converter

Convert binary to decimal using power-of-two summation

Binary Input
Decimal Result
42
101010 = 42
6 bits
Max: 63

Related Number Tools

How Binary to Decimal Conversion Works

Binary (base-2) uses only 0 and 1. Each position represents a power of 2, from right to left: 2⁰, 2¹, 2², etc. To convert, multiply each bit by its place value and sum: 1010₂ = 1×8 + 0×4 + 1×2 + 0×1 = 10₁₀. Our calculator handles up to 32-bit numbers instantly.

Frequently Asked Questions

What's the largest binary I can convert?
Our converter handles up to 32 bits (4294967295 decimal). For larger numbers, the result may overflow. Use 64-bit mode for bigger values.
Why is binary used in computers?
Computers use binary because transistors have two states: on (1) and off (0). This makes binary the natural language for digital circuits and data storage.
How do I convert decimal back to binary?
Divide by 2 repeatedly, reading remainders backward. Or use our other tools: we have a decimal to binary converter in the related tools section.