My youngest biological sister graduated at 15. I have 4 stepsister younger than her.

I was 16 when I started Senior Year, 17 when I graduated. I was one of the youngest in the class except for a few people who came from places where they could skip a grade. I kind of wish my parents hadn't started me in Kindergarten a year early, though. But it wasn't horrible.

Among my friends, some graduated at 17, some at 18. It's no biggie. The natural variation in maturity of HS seniors is pretty large and not entirely age dependent. However, IF he's struggling in his classes, lack of maturity might be part of the reason.

I was 17 all of senior year butmy birthday is in June right after the end of the school year.

I was 18 when I graduated. Though I have friends that were 17 because they have summer birthdays.

17-18. I'm sure he will be ok

Quite.

Both my boys were 18

August birthday?

I was 17 at graduation too

My daughter was 17 when she graduated.

We have a different system, here you can graduate at 17, 18 or 19 depending on the type of the school and whether you were born early or late in the year.

Yes, for most. Some a bit earlier or later.

Dan was 18 when he graduated this year

My son graduated and was 17 .so I'd say normal
I was 17 as well

I was 17 at graduation

Normal. I was 17 when I graduated HS. If I remember correctly I must've started the senior year at 16 just few days before my 17th birthday since I'm a September baby.

He must have a late birthday.

17

Yes seniors graduate at 17 or 18 years old this is completely normal

It is young, especially amidst a global bloody pandemic as there were extended periods of lockdowns all over the world.
Normal is a strange word nowadays.