Understanding mortgage refinancing
How amortization works
A fixed-rate mortgage is repaid on an amortization schedule: the same payment every month, split between interest and principal. The split changes over time. Early on, most of your payment goes to interest because the balance is large; only a small sliver pays down principal. As the balance falls, the interest portion shrinks and more of each payment chips away at what you owe.
This is why the first years of a mortgage feel like you're barely making progress — the interest is front-loaded. The payment formula is M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is the loan amount, r is the monthly rate, and n is the number of payments. The amortization table below shows exactly how the split evolves year by year.
The real power of extra payments
Because interest is charged on the remaining balance, every extra dollar you pay toward principal stops accruing interest for the entire rest of the loan. On a 30-year mortgage, an extra $200 a month can cut years off the term and save tens of thousands in interest. The effect compounds: the earlier you make extra payments, the more interest you avoid.
Extra payments don't just shorten the loan — they redirect money that would have been interest straight into your own equity.
Should you refinance?
Refinancing replaces your current mortgage with a new one — ideally at a lower rate or a shorter term. It can save money, but it isn't free: closing costs, appraisal fees, and a fresh amortization schedule all factor in. The rule of thumb is to calculate your break-even point: divide the total cost of refinancing by your monthly savings to see how many months it takes to come out ahead. If you plan to move before then, refinancing may not pay off. Use Compare mode above to see two scenarios side by side.
Rolling in credit card debt
A cash-out refinance can roll high-interest credit card debt into your mortgage at a lower rate — and the lower rate is tempting. But it converts short-term debt into 30-year debt. A $15,000 card balance you might have cleared in three years now rides along at mortgage interest for decades. Even at a lower rate, the total interest paid on that balance can dwarf what you'd have paid by attacking it directly.
Think of it as a permanent pay cut: your monthly mortgage payment rises and stays risen for the life of the loan. Before you roll anything in, it's worth seeing the true cost of that card debt — which is exactly what the Pay Down app is built to show.