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BCD Converter
Convert between decimal and packed or unpacked binary coded decimal, with invalid nibbles flagged.
Binary coded decimal
Result: —
Nibbles: —
How to use the BCD Converter
- Choose whether you are converting from decimal or from BCD.
- Pick packed BCD or unpacked BCD for the digit layout.
- Read the nibbles, the hex form and any validation note.
Features
- Packed and unpacked BCD both ways
- Nibble and hex views of every result
- Invalid nibbles above 1001 are rejected
- Negative values supported in packed BCD
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Frequently Asked Questions
Common questions about the free online bcd converter.
BCD stores each decimal digit separately in four bits, so 42 becomes 0100 0010 rather than
the plain binary 101010.
Packed BCD puts one digit in each nibble, while unpacked BCD gives every digit a full byte
with a zero high nibble.
One byte holds exactly two decimal digits, one in the high nibble and one in the low nibble.
Packed BCD uses a 1101 nibble in the leading position to mark the value as negative.
Only nibbles 0000 to 1001 are valid digits. Anything above 1001 has no decimal meaning, so it
is flagged as invalid.
No. BCD keeps decimal digits intact, so it is longer than plain binary but much easier to
display on seven segment hardware.
It appears in digital clocks, calculators, cash registers and older decimal arithmetic
hardware.
Yes. Every digit is handled as a nibble, so any number of digits can be converted.
Yes. Packed results are also shown as a hex byte string, which is how they usually appear in
memory.
Yes. The conversion happens in your browser, is completely free and uploads nothing.
Last updated: October 10, 2026