BCD Encoder

Convert decimal digits to and from Binary-Coded Decimal — the digit-per-nibble encoding used in electronic displays, financial calculators and the COBOL COMP-3 packed type. Supports the natural 8421 (BCD) and Excess-3 (XS-3) variants, in both packed (two digits per byte) and unpacked (one byte per digit) layouts, with a full digit-to-nibble reference table. Pure arithmetic, in your browser.

Variant 8421 (natural BCD) Excess-3 (XS-3)

Layout Packed (2 digits/byte) Unpacked (1 digit/byte)

Decimal digits

Only the characters 0–9. In packed mode an odd digit count is left-padded with a 0 (encoded as 0 in 8421, 3 in XS-3).

Digit → nibble mapping