[jdeisenberg]

A gallon of water weighs 8.3 pounds, so your estimate of 10 pounds is about 20% too high. To add to what someone else posted in terms of metric to “intutive” equivalences, 1 km is about 600 paces (for me, it’s also the distance from my house to the Asian market)

People living in metric countries have these sorts of “intuitive” relationships figured out. If you ever go to Europe, you will not see people anxiously furrowing their brows over their calculators to figure out how much things weigh or how far it is to the end of the block.

And, of course, there’s an XKCD for that: https://xkcd.com/526/