Estimate the monthly payment and total cost of any fixed-rate loan.
A fixed-rate loan is amortized: every payment is the same size, but its composition shifts over time. Early payments are mostly interest, because the outstanding balance is large. As the balance shrinks, more of each payment attacks the principal, until the final payment is almost entirely principal.
On a $300,000 mortgage at 6.5% over 30 years, the monthly payment is about $1,896 and total interest exceeds $382,000. That is more than the house itself. This is why the term length and rate matter so much: a 15-year version of the same loan at 6.0% costs roughly $156,000 in interest, less than half as much.
Where M is the monthly payment, P the loan amount, i the monthly rate (annual rate divided by 12), and n the total number of payments.
No, this shows principal and interest only. For a full housing cost picture, add property tax, homeowners insurance, and any HOA fees.
This calculator assumes a fixed rate. For adjustable-rate mortgages, model the worst case using the maximum rate allowed by your loan terms.
Not necessarily. If your rate is low and you can reliably invest extra cash at a higher return, the longer term can win. But that requires discipline; the shorter term forces the saving automatically.