How many books should your school library have?

Rather than relying on quantitative standards for tire pressure or oil life that promote compliance with an inflexible and minimal threshold, automobile owners need to demonstrate the dispositions of deep commitment and inquiry required by continuous tire and engine wear monitoring.
Sometime we need actual numbers...
This came across LM_Net a week or so ago:
I am looking for a recommended number of library books per student and it appears that the AASL no longer recommends an actual number.
Yup, AASL has not included quantitative recommendations in it standards for 20 years. In fact, it has a 2013 position statement that reads in part: Rather than relying on quantitative standards that promote compliance with an inflexible and minimal threshold list, school librarians need to demonstrate the dispositions of deep commitment and inquiry required by continuous program assessment and advocacy with stakeholders. (AASL, National School Library Standards for Learners, School Librarians, and School Libraries, 2018 p216)
So commitment is the judge of the adequacy of a collection. You, and you alone, as a professional determine how many materials your library needs. Why do I think a lot of school administrators will simply roll their eyes when you tell them this?
When AASL abandoned quantitative standards for school library programs with the publication of the 1998 version of Information Power, Minnesota librarians stepped up and included them in their 2000 Minnesota Standards for Effective School Library Media Programs:
Other states, including Texas, have done the same with more recent revisions of their own standards.
For better or worse, a lot of decision-makers like hard numbers that come from an authoritative source. Too bad AASL or other national organizations which might lend some weight to budget requests based on collection size and age refuses to provide them for terribly idealist reasons.
Hopefully other organizations will fill this void.