The problem I have with buy vs rent calculators is that the speculative questions often end up dominating the decision. How much will rent go up in the place you rent? Nobody knows. How much will the value of the property appreciate during the period you own it. Again, this is unknowable. So you put in a range of guesses for these, and you can get it to come out as a good or bad investment depending on what you guess.

My guesses were ludicrously wrong when I did these back in 2018, relative to what has actually happened in both the rental market where I live, and the value of the house I bought. I concluded that the reason to buy was only about the non-financial aspect, and that we'd probably lose a little money all told. But it has turned out to be a six figure win in practice. Rent has gone way up, we were able to refinance to one of these very cheap loans during covid, and the property value spiked around the same time. I never would have guessed any of that. And any of it could have gone the opposite way.

So the calculators were honestly pretty useless. It's all too unknowable.