<p>This is actually easy. Find a development letter from the school that explains the difference between annual tuition charges and the ACTUAL cost per student per year. Let’s say as a guesstimate it’s $7500. You have to give at least that figure annually, and I would say safer to double it. If the school knows you are willing to pay the TRUE full cost of your kid’s education, PLUS subsidize the gap for another student, then you are in the ballpark. Obviously, the larger the school’s endowment and application numbers, the more selective they can be, but I can assure you this is how to calculate the baseline answer for your question.</p>