It's true that the vast majority of the world uses only metric but Western English speaking countries tend to use a mix.

The UK is mixed, Ireland (where I am) is mostly metric but a person's height is still mostly imperial and butter is sold in 454g packs (a pound) and older folks still measure their weight in stones and pounds, Canada uses a mix (my sister lives there and we discussed this recently) and the US uses metric where appropriate (science, military, medicine).