In the UK, you would be able to ask "At what age did you finish studying?" to lead to the same thing. If the answer was "16", I would know the person finished secondary school (having taken CSEs, O Levels or GCSEs). If the answer was "18", then I would know they finished college (A Levels at Sixth Form College or a vocational course at technical college). I they said "21" or "22", then I would be pretty confident that they completed university.
In the UK, we have only recently started using "4th grade", "11th grade" etc. It has been adopted from the American system I think. I still have to work it out mathematically when someone says that their child is in "X grade". I take the number of the grade and add it to 5 (the age at which a child starts school). So after doing the sum, I understand that a child who is in 8th grade is 13 (approximately). For me, that means they're in their second year of secondary school!
When I was at school, I was in "Fives/Sixes/Sevens/Eights" (first/primary school), then class "1C, 2E, 3L and 4S" (middle/junior school) and "Second year, third year, fourth year and fifth year" at secondary school. At sixth form college, I was in the Lower Sixth and then Upper Sixth.