Perhaps having a converter conveniently on the page would make it easier? Either to add a conversion or just to see the size in a familiar measure. I know it is hard to change, Canadians have done it in about a generation but there are still lots who have a better sense of one than the other. I've had to convert to metric since I retired and moved to Mexico, most is pretty easy but temperature is not a simple conversion. I'm comfortable with kilometers, liters, cm and kilos but I had to just start over and learn my personal comfort levels in centigrade rather than convert. I still will sometimes look at a conversion to fahrenheit just because it gives me a better idea.
I think that both sides of the argument have good points, the world is mainly metric but no one should be forced to convert from something that is comfortable. If the US continues to want to stay with their unique system of measure, then they should. If I were voting on it, I'd say the US should take its time and convert over the next generation as Canada seems to have done. It doesn't matter to kids, they learn what is taught to them and then they are comfortable with it. Start in the schools and let the older generations keep their measures, maybe have both on everything for awhile.
