Have you ever wondered what the 'e' symbol on many packaged goods meant? Not the 'E' followed by a three figure number in the list of ingredients (the infamous 'E' number), but the large lower-case e that appears after the weight or volume on items from cans of fizzy drink to tins of beans and bars of chocolate. While it fairly obviously has some meaning related to the size of the product, what the meaning is is not as well-known as the more familiar (to British researchers) kitemark indicating the manufactured product meets some particular British Standard.

What does it look like?

If you have no packaging around with the mark on you can see what it looks like here. Its design is a standardised shape of a sans serif¹ lowercase e with straight inner contours. This shape can be considered a logotype², and has been defined as a Unicode character with the designation U+212E.

• at least 3mm high
• in the same field of vision as the statement of nominal quantity
• indelible, clearly legible, and visible under normal conditions of purchase

Who is it for?

It is used in Europe for product packaging to show the estimated volume of the product, and is for the benefit of customs and trading standards officials. The 'e' mark on goods provides exemption from some laws relating to weights and measures, thus allowing these goods to be moved more simply throughout the EC without tedious rechecking at borders. This has allowed the emphasis for enforcement of trading standards to move from the retail level to controls where the goods are manufactured, packaged or imported.

What does it signify?

Traditionally the practice of selling by weight or volume works on the basis that the purchaser does not get less than what they are paying for. The 'e' mark allows for the potential inaccuracies of packaging systems and gives the important assurance that:

• The actual contents of the packages shall not be less, on average, than the nominal quantity stated.

There are no regulations on being given more than you are paying for, but obviously it is uneconomic for manufacturers to do that. The impetus of the regulations is to ensure packaging is reasonably accurate. In addition there are two further rules, specifying how much inaccuracy is allowed, that must be satisfied before the mark can be used:

• Not more than 2.5% of packages³ may be non-standard, ie have Tolerable Negative Errors (TNE) greater than that specified for the particular nominal quantity.
• No package may be inadequate (ie be deficient) by more than twice the TNE.

In other words: not only is the item a certain size, but only rarely will it be less than that size, and never by more than a small amount.

Want to know more?

The 'e' mark relates to a very small part of the history of metrology, the science of weights and measures. The specific use of the mark is defined in European Directive 71/316/EEC (pdf file), or, as far as UK implementation of the directive, in the Weights and Measures Act 1985 Part V.

The entry on 'Units of Measurement' will tell you more about the SI⁴ measures used by the metrological machines to give standard comparisons.