How This Calculator Works
Most mortgage calculators show you one number: your monthly payment. This one goes further by combining two things buyers almost always want to know together but rarely find in the same place — what happens to your payoff timeline when you add extra principal payments, and exactly when your private mortgage insurance (PMI) will fall off your bill as a result.
Extra Payments and Amortization
Every dollar you add to your monthly payment beyond the required principal and interest goes straight toward reducing your loan balance. Because mortgage interest is calculated on the remaining balance each month, a lower balance means less interest accrues going forward. Over time this compounds: each extra payment shortens the loan and reduces the total interest paid over its life, often by tens of thousands of dollars on a 30-year loan.
When Does PMI Go Away?
If your down payment was less than 20% of the home's value, your lender likely required PMI to protect against default risk. Under federal law, lenders must automatically cancel PMI once your loan balance drops to 78% of the home's original value, assuming you're current on payments. You can also request cancellation earlier, once you reach 80%, though the lender may require an appraisal. Extra payments can pull that date forward by months or years compared to the standard schedule.
Reading Your Results
The PMI removal date reflects the month your balance crosses the 78% threshold under your accelerated schedule. The payoff date shows your new loan-end month, while the comparison figures quantify how much time and interest your extra payments save versus paying only the required amount. The table below breaks down the full schedule month by month, with the PMI removal month highlighted.