An argument made against metric-only labelling in the US is that manufacturers would need to change packaging to rational metric sizes. Ronnie Cohen looks at the UK’s experience over the past 50 years.
The need to change package sizes is sometimes seen as an obstacle to the adoption of metric-only labelling in the US, and may also be a reason for the continued use of supplementary indications in the UK and, to a lesser extent, in the EU. We will therefore examine the myth that:
“Metric-only labelling requires changes to package sizes.”
When there is a transition from imperial to metric in manufacturing, there are two ways to manage the change, namely hard metric conversion and soft metric conversion (and no, this has nothing to do with Brexit).
Hard metric conversion
In the context of metrication, a hard conversion occurs when an imperial-based package size is rounded off to a close rational metric size. For example, packs and tubs of butter used to be sold in half pound (227 g) and one pound (454 g) sizes. Now, they are usually sold in 250 g and 500 g packs. This is an example of hard conversions where the packages were changed to rational metric sizes.
Here are a couple of examples of products sold in rational metric sizes:
Soft metric conversion
Products labelled exclusively in metric do not need to be sold in rational metric sizes in the UK. There are many examples of products that underwent soft metric conversion. For example, jam is still still sold in the same sizes as before the metric changeover. The only thing that has changed is the weight shown on the label; they now show 454 g instead of 1 lb and the 12 oz jar lives on as 340 g. However, other suppliers have switched to the metric rational sizes of 450 g and 500 g.
Here are a couple of examples of products sold in non-rational metric sizes:
Bottled beer is occasionally sold in pint-sized bottles but labelled exclusively in metric units. While there is some beer and cider on sale in the UK in pint-sized bottles and/or cans, beer and cider sold in supermarkets and off-licences are mostly sold in rational metric sizes. And, of course the supermarkets sell fresh milk in rational imperial sizes, 1/2, 1, 2, 4 and 6 pints, whereas the corner shop and the garage will probably stock rational metric sizes, 500 mL, 1 L and 2 L.
The notion that metric-only labelling will require round metric package sizes is unfounded. When the US Fair Packaging and Labeling Act eventually allows metric-only labelling, manufacturers are likely to have a choice between hard conversion and soft conversion.