Code 128 and Code 39: The Barcodes Behind Labels and Warehouses

Product barcodes are only one type. Warehouses, offices and shipping companies often use others.

Code 39

Code 39 is one of the older barcode types. It can encode:

• digits 0–9
• capital letters A–Z
• a few symbols, such as the dash and the space

It is called "39" because the original character set had 39 characters. Each character is made of bars and spaces, and the code is simple to print, so it has been popular for asset tags, ID badges and some industrial labels.

Code 128

Code 128 is denser. It can encode the full set of ASCII characters, including lowercase letters, and it packs digits especially tightly in pairs. It has a built-in check character.

You will often see it on:

• shipping and parcel labels
• inventory labels
• serial numbers on equipment

Comparing them

	Code 39	Code 128
Characters	limited set	full ASCII
Density	lower	higher
Error checking	optional	built in

One-dimensional codes

Both are linear barcodes. They are read along a single line, so the scanner must be lined up across the bars, and they hold much less than a QR code.

Meeting them in daily life

• The label on a parcel
• The sticker on electronics
• A library card or membership card
• A visitor badge

Tips

1. Scan the whole width of the bars.
2. Avoid glare on shiny labels.
3. Keep the code flat.

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