A full amortization schedule with PMI tracked month by month, plus what happens if you add extra principal payments. Change any field and the schedule, chart, and payoff dates update instantly.
How this calculator works
A mortgage payment is the same number every month, but what it buys changes completely. In year one of a 30-year loan at today's rates, roughly 85 cents of every dollar you pay is interest; it takes close to twenty years before principal is even half of the payment. An amortization schedule is simply that split, month by month — and once you can see it, extra payments stop being abstract, because you can watch exactly which months they delete.
Each month, interest is the current balance × r; the rest of the payment is principal. The balance drops by that principal, next month's interest is slightly smaller, and the split tilts a little further toward principal. That's the whole mechanism — the curve on the chart is that tilt accumulating.
If your down payment is under 20%, private mortgage insurance is added at the annual rate you set (0.55% of the loan by default) until the balance falls to 80% of the original price. This schedule assumes you request cancellation the month you become eligible — by federal law it would otherwise run to 78% or the loan's midpoint. The "PMI drops off" stat shows that month for the standard schedule and for the schedule with your extra payments, which is where the extra payments earn their keep twice: less interest and fewer months of PMI.
Add an extra monthly amount, an extra yearly amount (a tax refund in month 12, say), or both, each with its own start month. Extra money goes straight to principal, so it shortens the loan rather than lowering the payment. The chart overlays both balances so you can see the gap open up, and the stats show total interest saved and the new payoff date. A common surprise: $200 a month on a $250,000, 30-year loan at today's rates removes about eight years and close to $100,000 in interest.
Property tax, homeowners insurance and HOA aren't part of an amortization schedule — they don't touch the loan balance. For the full monthly cost, run the Home Affordability calculator, which adds them and grades the result.
It depends on the rate. Paying down a 6.5% mortgage is a guaranteed 6.5% return; over long periods stocks have averaged more but with real risk. A common middle path is to fund retirement accounts to any employer match first, keep an emergency fund, then split what's left. The 15-vs-30-year guide shows the same trade-off from the other direction.
A 15-year usually carries a lower rate, which a 30-year with extra payments can't match. But the 30-year keeps the minimum payment small if money gets tight — you can always pay extra, you can't pay less. Run both here and compare total interest.
Because the rule is based on the original purchase price, not today's value — reaching 80% loan-to-value of the original price is what earns the cancellation request. If your home has appreciated, you may be able to cancel earlier with a new appraisal; the PMI guide walks through how.
No. With a standard mortgage the required payment stays the same and the loan ends sooner. If you want the payment itself lowered, that's a recast (a lump sum plus a lender fee) or a refinance — different products entirely.
Last reviewed September 2026. Read our methodology for every source and assumption, and the calculator disclaimers for what these estimates are and aren't.