How many schools should you apply to?

If you're considering private, the answer is three to five, plus the SFUSD application.

That's enough to give your student options in San Francisco without drowning your family in work, and that second part matters more than people realize. Every school you add is another set of visits, another essay or three, another interview, another round of your student figuring out how they feel. Schools vary a lot in how much they ask: some take a common application and a shared essay, some tack on short extra questions, and some run their own bespoke process that demands a chunk of your fall. You don't find out how heavy a school is until you're inside it.

Three is right if three is your honest list. Going below that gets a little nerve-wracking, but if there aren't three schools that fit your student, that's worth facing rather than padding the list with places you don't mean.