Mortgage calculator — Real Estate Investment Insights

What this calculator is actually doing

The large payment is principal and interest on a fully amortizing fixed loan: price minus down payment, at the rate and term you set. It is not PITI. Taxes and insurance are not inside that hero number.

Investment metrics on the same page borrow a 1.5% of purchase price per year stand-in for taxes + insurance + maintenance, then subtract that twelfth from rent to invent “cash flow.” Cap rate uses the same plug. Cash-on-cash divides that annual remainder by cash down. GRM is price / (rent × 12). The “debt coverage” ratio here is rent / P&I, which is not lender DSCR (NOI / total debt service).

If those shortcuts are close to your market, the page is a decent first screen. If you are in a high-millage county, a wind/hail state, or an HOA, replace the plug with the expense-stack worksheet before you quote a monthly number to yourself.

Worked default on the sliders

At $400,000, 20% down, 6.82%, 30 years, the loan is $320,000. P&I is about $2,090. A $2,800 rent minus P&I minus a $500/month 1.5% plug prints a small surplus. Move insurance to a real $240 quote and taxes to a post-sale $380 and the surplus is gone. That is the lesson, not the default.

Next: underwrite rent first, then reopen this page with honest rent.

The interactive controls load with JavaScript.