I get totally confused lol. I think in feet and inches and in centimetres, depending what it is I'm thinking about. The same with fluid ounces and mls. I can only think in fluid ounces for cooking but when I was nursing, we had to measure urine and saline in mls so I can eyeball a litre of liquid ha ha.
So for measuring room sizes I can think in feet and inches only, not metres. But for hamster cages I have to convert the inches into centimetres so I know how big it is