Unveiling the Mystery: What Do the Numbers Under Glass Bottles Mean?

Glass bottles are ubiquitous in our everyday lives, from beverage containers to cosmetic packaging. But have you ever wondered about the significance of the numbers and symbols etched at the bottom of these bottles? This article aims to unravel the secret behind these mysterious markings.

Unveiling the Mystery: What Do the Numbers Under Glass Bottles Mean?

The Language of Glass Bottles

The numbers, letters, and symbols at the bottom of glass bottles might seem like random imprints, but they serve a vital purpose. These so-called bottle codes offer insights into the manufacturing process, the origin of the bottle, and sometimes even its age1.

The Manufacturer’s Signature

One of the primary pieces of information that these markings provide is the identity of the manufacturer2. Much like an artist signing their work, glass manufacturers imprint their logo or initials on the base of the bottle. This allows for easy identification and serves as a mark of quality assurance.

Glass Honey Jar Drawing

Mould and Cavity Identification

Mould equipment identification numbers and cavity identification are also common elements found on the bottom of glass bottles2. These numbers help trace the exact mould used in the production process, providing valuable information for quality control and maintenance purposes.

Deciphering Dates and Distilleries

Certain types of bottles, particularly those used for beverages, may carry additional unique markers. For instance, beer and liquor bottles often have “D-numbers” on their bases34. These identifiers correspond to specific distilleries, allowing consumers and collectors to trace the origins of the beverage.

Standardisation Symbols

If a glass container is standardized, it may bear the symbol “M” or the symbol “ε”5. The “M” symbol is typically used for products whose capacity is less than one liter. These symbols ensure that the containers meet certain standards, guaranteeing uniformity across different batches and manufacturers.

Age and Antiquity

For collectors and enthusiasts, the numbers at the bottom of old glass bottles can provide clues to their age6. One- or two-digit numbers usually represent mould numbers. However, they can also identify specific areas in an automatic bottle maker, helping to date the bottle.

Dot-shaped automatic identification code

The Famous “57”

Some numbers carry brand-specific significance. A notable example is the number “57” etched into the glass neck of every Heinz ketchup bottle7. This originates from the brand’s famous “57 varieties” slogan, serving as a subtle nod to the company’s rich history.

Dot-shaped automatic identification code with mold number


In conclusion, the numbers under the glass bottle are much more than random markings. They tell a story about the bottle’s origin, its journey through the manufacturing process, and sometimes even its age. So the next time you hold a glass bottle in your hand, take a moment to flip it over and read the story that lies beneath.

Dot-shaped automatic identification code table


  1. O-I
  2. YouTube 2
  3. NoNameHiding
  4. True Legacy Homes
  5. Stoelzle
  6. Quora
  7. New York Post

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