If you haven’t seen this before, it’s a very detailed and customizable rent-vs-buy calculator. It assumes that all else being equal, you can compare apples-to-apples options for your shelter. If buying costs more, the renter will save the difference in monthly cash flow and invest it. It allows you to model a change in interest rates over time (specifying a rate for years 1-5, 5-10, and 10+), includes the effect of transaction fees, house price appreciation, taxes on the renter’s investments, and most importantly: investment returns that compound over time.