How hard is it to take 4 AP classes?

I’m planning to take 4 AP classes my junior year:
AP Calculus AB
APUSH (US History)
AP Physics C
AP Language
How hard are these classes (based on your experiences) and what do you do in the classes (what do you learn)?

Not too hard. AB’s pretty straightforward, as is APUSH. Physics C can be a bit of a drain, as can lang.

I take:

AP stats
AP comp
AP psych
AP Econ
IB enviro

This semester and I am a senior… And leader of 3 big ECs and run varsity track,You can handle it

It depends on your abilities and the quality of the teachers. For many, 4 is doable; for others, not so much.

Nah it’s fine - these are definitely doable (though skieurope is right, it depends on ability). At least in my experience, I have taken 4+ APs at a time (similar ones to yours), and I found it okay.