u/dhavalpalsana

I built a free web tool: a true rent vs buy calculator for US homes.

Most calculators just compare mortgage payment vs rent. That’s incomplete.

The interesting question is: What happens to your net worth if you put the same money into a house or into investments, after taxes, maintenance, PMI, selling costs, and the fact that equity isn’t cash until you sell?

What it models

• Same starting wealth on both paths (down payment + closing costs either buy the house or seed a portfolio)
• True ownership costs: P&I, property tax on rising value, insurance, HOA, maintenance, PMI until LTV drops
• Opportunity cost every month — whoever spends less on housing invests the difference
• Terminal sale with selling costs (so “equity” isn’t free money)
• Optional interest + property-tax shield at your marginal rate
• Year-by-year ledger, break-even year, and sensitivity (what if rates / rent / appreciation move?)

Extra modes people usually don’t get

• % or $ for down payment, closing, and selling costs
• Liquid asset buckets — cash / stocks / bonds with different returns, and whether to use them for the down payment
• I already own — keep the house vs sell today, invest the proceeds, and rent (optional simple capital gains)
• Today’s dollars — deflate long-horizon wealth with inflation so a 20-year number doesn’t look fake-rich
• Loan-term marker on the charts so you can see when the mortgage actually ends

It’s a client-side educational model, not tax/lending advice — deliberately transparent rather than a black box.

Live tool (Engineering Toolkit):

https://eng-toolkit.web.app/tools/rent-vs-buy/

Not strictly an engineering tool — pure personal finance — but it was fun to build, so I shipped it with the rest of the toolkit. 100% vibe-coded; any feedback is welcome.