Cool calculator.
One thing that is missing is the opportunity cost of the down payment.
Also, in fairness, the renter scenario should be a smart renter that invests their money. Typically, a renter will have lower monthly housing costs in the beginning and will have more money for investment.
Ideally, the net worth should be compared after 25 years or something.
Hey folks, I built this NPV calculator in Python a couple years back, before I bought my first house. Here it is again, rewritten it in React/Recharts. Let me know if its helpful and if you have any feedback!
If you add annual maintenance costs, then your calculator would be something I would recommend to people who are considering purchasing a house. I've seen suggestions that the annual cost would be 1% of the total house value, but I've also seen a value for that as high as FOUR percent!
https://www.thebalance.com/home-maintenance-budget-453820
The mortgage market is very lucrative when it comes to adsense and other monetization strategies. If you could find a way to market what you've created, you could manage to generate significant passive income (a.k.a., the gift that keeps on giving).