Free Binary to Decimal Converter
The CCNA exam expects you to convert between binary and decimal without a calculator. Tap the bits below to learn the place values, or type a value to convert.
Tap-the-bits interactive converter
Click any bit to toggle it between 0 and 1. The place value is shown under each bit.
Binary → Decimal
Accepts 8 bits, with or without dots/spaces: 11000000 or 1100 0000.
Decimal → Binary
Enter one octet (0–255). For a full address, convert each octet separately: 192.168.1.1.
Place values to memorise
The exam shortcut: memorise the eight place values. Every binary-to-decimal conversion is just adding up the positions holding a 1.
| Bit | 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
|---|---|---|---|---|---|---|---|---|
| Example: 192 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
192 = 128 + 64. Example: 168 = 128 + 32 + 8 → 10101000 | ||||||||
Subnet masks are just runs of 1s: 255.255.255.0 = 24 ones → 11111111.11111111.11111111.00000000. Drill this with our free subnetting drill.
Binary is step one — subnetting is the exam
Take the free 25-question CCNA mock test and see how your conversions hold up under time pressure.
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