WashU vs UC Berkeley

Please help in deciding between WashU vs UC Berkley. Majoring in Econ, California in state, no financial aid from WashU.
Thinking about placement. Would class size matter? I am assuming econ at UCB is higher quality academically than at WashU.

You can compare class sizes on the on-line schedules. WUStL classes are smaller, but not necessarily small.

https://courses.wustl.edu/Semester/Listing.aspx
http://schedule.berkeley.edu/

WUStL’s intermediate microeconomics course does use multivariable calculus; UCB offers intermediate microeconomics with multivariable calculus (101A) or with single variable calculus (100A). Both should be fine; if you want to go on to PhD study in economics, choose the more math versions whenever you can, and take additional math and statistics courses as suggested at https://www.econ.berkeley.edu/undergrad/current/preparing-for-grad-school .

Be aware that you do need a 3.0 GPA in the prerequisites to enter the economics major at UCB.

Of course, in the absence of any really big reasons to choose one over the other, the very large price difference argues in favor of in-state UCB over list price WUStL.