How the payment is calculated
Monthly principal & interest uses the standard amortization formula: M = P·r·(1+r)ⁿ / ((1+r)ⁿ−1), where P is the loan amount, r the monthly rate, and n the number of payments. Property tax and insurance are added on top as monthly escrow.
Questions
Is this an estimate or a quote?
It's an estimate for planning. Your actual rate, taxes, insurance and any HOA or PMI will come from your lender.
What does the bar show?
The share of every dollar you'll pay that goes to your principal versus interest across the whole loan.
Does a bigger down payment help?
Yes — it lowers the loan amount, the monthly payment and total interest. Try changing it above.