Coming at this from the other side, only worse! Growing up it was a toss-up as to which measurement was used: the natural things for me are a pound of butter but a kilo of sugar; people's heights in feet and inches but all other lengths in metres; a pint of milk or beer but all other liquids in ml, and so on...
I'm mostly metricated now, and I've no idea what an ounce looks like, or how many there are to a pound, but I have a good feel for what a pound is...
I'm best at converting lengths, because I do square foot gardening (30cm) and knit gauge swatches (4ins/10cm) but that doesn't help me when it comes to soap!