Base 10
Decimal uses ten digits: 0 through 9.
Number Systems Tool
Decimal to Binary Converter
Convert decimal numbers to binary and see the step-by-step division method behind the answer.
Big idea: Decimal uses base 10. Binary uses base 2. To convert a whole decimal number to binary, divide by 2, record each remainder, then read the remainders from bottom to top.
Decimal to binary converter
Enter a whole decimal number. The converter gives the binary answer and can show the full calculation.
Base 10
Binary result
101010
How 42 converts to binary
Divide by 2 and keep each remainder. Read the remainders upward.
Remainders upward: 101010So 42 in decimal is 101010 in binary.
Decimal42
Binary digits6
Highest place2^5
Number typePositive integer
Decimal to binary: divide by 2Each remainder becomes one binary digit. The last remainder becomes the first digit.
Why binary matters
Computers use binary because electronic switches can be off or on. Off is 0 and on is 1.
Convert to other bases
Use this base converter for common conversions like binary to decimal, base 16 to decimal, decimal to base 16, decimal to octal, and more.
Base 2
Converted result
42
Input baseBinary
Output baseDecimal
Tip for hexadecimal
Hexadecimal uses digits 0-9 and letters A-F. For example, decimal 255 is FF in base 16.
What students should remember
Base 2
Binary uses only two digits: 0 and 1.
Base 16
Hexadecimal is compact and often used in computing.
Practice keywords
Use this decimal to binary converter to practice binary numbers, base conversion, binary to decimal, hexadecimal, octal, and number systems.
decimal to binary converterbinary to decimaldecimal to hexbase converternumber systemshexadecimal