Actually, the inch (and probably other) US system measurements have been DEFINED as a function of the metric system since the '70s (an inch is now EXACTLY 25.4mm, not 25.400051... as it was previously). So the inch is therefor a metric unit! Personally, I use miles for distance, meters for altitude, liters for fuel, ounces for (most) liquid food products (and some dry), grams for most dry food products (and some liquid), and whatever temperature scale that happens to be convenient at the time. Tom