It just occurred to me that my idea of a unit may not be the same as the rest of the community.

I've been thinking of a unit as a standard US drink. That would be 12oz 5% beer, 1 (1.5oz) shot 40% liquor, etc.

But then I see there is also this concept of a UK unit that is like half the amount of alcohol as a US drink.

What is the preferred measure here?

It's very easy for me to remember and track when I had 1 beer or 1 shot. Trying to track when I've had 250 ml of 4% beer does not seem like it would be very easy to do

It doesn't matter so much, as long as you stick with the same standard throughout.