The USA and some other countries are not using the SI-system. Are there any estimates of how much productivity is lost because of having to convert numbers? (non-SI countries, SI-countries)
I imagine that the loss not only affects the non-SI countries, because the SI-countries wanting to export to non-SI countries would also use time for conversions in order to comply with local laws and customer demands.
The costs are probably difficult to measure because they are small amounts that are across every industry. For example car companies having to switch the km/h to mph speedometer; schools that have to spend much more time on explaining the non-SI system; or the the many goods that need double labelling.