Binary is a base-2 number system that uses only two digits: 0 and 1. It is the fundamental language of computers.

How do I read a binary number?

Read each digit from right to left. Each position represents a power of 2 (1, 2, 4, 8, 16, ...). Add up the values where the digit is 1.

Binary to Decimal Converter

Convert binary numbers to decimal. Enter each binary digit position to build the number. Free binary to decimal converter.

Save

Bit 7 (128s)

Bit 6 (64s)

Bit 5 (32s)

Bit 4 (16s)

Bit 3 (8s)

Bit 2 (4s)

Bit 1 (2s)

Bit 0 (1s)

Decimal Value

View formula & how it works →

Binary to Decimal Converter

How It Works

Each binary digit (bit) represents a power of 2. From right to left:

Bit 0 = 2^0 = 1

Bit 1 = 2^1 = 2

Bit 2 = 2^2 = 4

Bit 3 = 2^3 = 8

Bit 4 = 2^4 = 16

Bit 5 = 2^5 = 32

Bit 6 = 2^6 = 64

Bit 7 = 2^7 = 128

Multiply each bit by its place value and sum all the results.

Example Calculation

Convert binary 00010101 to decimal.

010×128 + 0×64 + 0×32 + 1×16 + 0×8 + 1×4 + 0×2 + 1×1
02= 0 + 0 + 0 + 16 + 0 + 4 + 0 + 1
03= 21 in decimal

Frequently Asked Questions

Learn More

Metric vs Imperial: A Complete Guide to the Two Measurement Systems

Understand the differences between the metric and imperial measurement systems. Learn their history, how they compare, and when to use each system for length, weight, volume, and temperature.

Binary to Decimal Converter

Binary to Decimal Converter

How It Works

Example Calculation

Frequently Asked Questions

Metric vs Imperial: A Complete Guide to the Two Measurement Systems

Related Calculators

Hex to Decimal Converter

Octal Converter