How comfortable are you at using metric?

As a native metric user, even though I've been constantly exposed to Imperial units through American media, I still struggle a lot. I can 'generally' visualise pounds, feet, farenheit, ounces, and miles, but to fully conceptualise them I have to convert to metric.

For example, when I read about the altitude of a plane in feet, I have to divide by 3 (into metres) to fully understand how far from the ground it is.

What about you? If you see something in metres, kilograms, or litres, how quickly do you understand the measurements?