Decimal to Binary Converter

Turn any decimal (base-10) number into binary. Type one number or several separated by spaces — each converts independently.

Quick examples

Try a decimal number.

Click any example to load it into the converter above — the binary appears instantly.

How it works

From base-10 to base-2.

Binary uses only the digits 0 and 1. Convert by repeatedly dividing by 2 and reading the remainders backwards.

Divide by 2

Take the decimal number and divide it by 2. Record the quotient and the remainder (0 or 1).

Record remainders

Repeat the division on each new quotient, collecting the remainders until the quotient reaches 0.

Read bottom-up

The binary result is the sequence of remainders read from the last one back up to the first.

Reference table

Decimal 0–15 in binary.

Memorize this small table and you can convert most small numbers by sight.

Decimal	Binary
0	0
1	1
2	10
3	11
4	100
5	101
6	110
7	111
8	1000
9	1001
10	1010
15	1111

Where this comes up

Common uses for a decimal to binary converter.

CS homework — verify your hand calculations for base conversions.
IP & subnet math — CIDR masks and addresses are easiest to reason about in binary.
Digital electronics — design counters, registers and logic gates from decimal specs.
Number system learning — build intuition for how place-value systems generalize beyond base-10.

FAQ

Decimal to binary, explained.

How do I convert decimal to binary by hand?

Divide the decimal number by 2 and write down the remainder (0 or 1). Keep dividing the quotient by 2 and recording remainders until the quotient reaches 0. Read the remainders from bottom to top — that sequence is the binary equivalent.

What is base-10?

Base-10, or decimal, is the everyday number system using the digits 0 through 9. Each position represents a power of 10. Computers store numbers in base-2 (binary) using only the digits 0 and 1.

Is there a largest number I can convert?

There is no hard limit in the converter itself — it handles arbitrarily large integers. In practice, very large numbers produce very long binary strings, so browsers may slow down on extremely large inputs.

How do I go back (binary to decimal)?

Use the Binary to Decimal tool, or simply swap direction in this converter. Each binary digit represents a power of 2 — sum the powers where the bit is 1 to get the decimal value.

Decimal to Binary Converter

Try a decimal number.

From base-10 to base-2.

Divide by 2

Record remainders

Read bottom-up

Decimal 0–15 in binary.

Common uses for a decimal to binary converter.

Go one level deeper.

Binary to Decimal

Binary Translator

Binary to Hex

ASCII Table

Decimal to binary, explained.