1. Enter a value
Type a number in the input field. You can use a period or comma as the decimal separator.
Convert decimal to binary
This converter converts decimal numbers to binary representation. Enter a number and the result appears instantly.
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When do you need to convert decimal to binary?
Binary (base-2) is the fundamental number system of computers. Every piece of data — text, images, programs — is stored as sequences of 0s and 1s. Understanding binary is essential for programming, networking, and computer science.
Each binary digit (bit) represents a power of 2: ...128, 64, 32, 16, 8, 4, 2, 1. For example: decimal 42 = binary 101010 (32+8+2).
Common uses: IP addresses, subnet masks, bitwise operations, permissions (chmod), and understanding how computers store numbers.
All calculations run locally in your browser — nothing is sent to any server.
How to use the converter?
2. Read the result
The conversion result appears instantly in the field next to it – no clicking required.3. Copy or reverse
Click Copy result or use the Reverse button to convert in the opposite direction.
When is this converter useful?
Programming
Bitwise operations, masks, flags: 0xFF = 11111111.IP Networks
Subnet masks: 255.255.255.0 = /24 (24 ones in binary).Unix Permissions
chmod 755 = 111 101 101 in binary.Electronics
Registers, I/O ports, communication protocols.
What makes this converter different?
Complete privacy
All calculations run locally in your browser. No data is sent to any server.Real-time results
The result updates instantly as you type – no need to click any button.Bidirectional conversion
The Reverse button lets you convert in both directions with one click.Reference table
A ready-made table with commonly converted values and contextual descriptions.
How does decimal to binary conversion work?
Repeatedly divide by 2 and record remainders. Read remainders bottom-to-top. Example: 42 ÷ 2 = 21 R0, 21 ÷ 2 = 10 R1, 10 ÷ 2 = 5 R0, 5 ÷ 2 = 2 R1, 2 ÷ 2 = 1 R0, 1 ÷ 2 = 0 R1 → 101010.
To convert binary to decimal: multiply each bit by its position value. 101010 = 1×32 + 0×16 + 1×8 + 0×4 + 1×2 + 0×1 = 42.
8 bits = 1 byte = values 0–255. 16 bits = values 0–65,535. 32 bits = values 0–4,294,967,295.
Practical tips
- Powers of 2: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024.
- 1 byte = 8 bits = 0–255. Common in RGB colors, ASCII codes.
- IP address: 192.168.1.1 = 11000000.10101000.00000001.00000001.
- Negative numbers use two's complement in most systems.
Decimal vs Binary
| Feature | Decimal (base-10) | Binary (base-2) |
|---|---|---|
| Digits | 0–9 | 0–1 |
| Used by | Humans | Computers |
| Example: 42 | 42 | 101010 |
| Example: 255 | 255 | 11111111 |
| Readability | Easy for humans | Long but computer-native |
Decimal (base-10)
- Digits
0–9 - Used by
Humans - Example: 42
42 - Example: 255
255 - Readability
Easy for humans
Binary (base-2)
- Digits
0–1 - Used by
Computers - Example: 42
101010 - Example: 255
11111111 - Readability
Long but computer-native
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Frequently asked questions
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