How the payoff date is calculated
Each month the lender charges interest equal to the outstanding balance times the annual rate divided by twelve. Whatever is left of your payment reduces the balance. Because the interest charge is recomputed on a smaller balance every month, every extra dollar compounds forward — the payoff date moves faster than the extra payment would suggest.
Paying $1,076 extra on this loan retires it in about 15 years instead of 30 and saves $318,393 in interest — more than the original down payment.
Payoff early or invest the difference?
Paying down a 6.5% mortgage is a guaranteed 6.5% return with no volatility and no tax on the gain. An investment has to beat that after tax to win. The calculator reports NPV against your chosen discount rate (defaulting to the 10-year Treasury) and an IRR on the full ownership cash-flow stream, so you can compare the two directly instead of guessing.
Reasons to keep the mortgage: a rate below current safe yields, unused 401(k) or IRA space, or a thin emergency fund. Reasons to clear it: a high rate, imminent retirement, PMI still attached, or simply preferring a fixed cost removed from your life.
Before you send the final payment
- Request an official payoff quote — it includes per-diem interest and fees.
- Confirm the lien release is recorded with your county.
- Move escrowed taxes and insurance onto your own calendar once the escrow account closes.
- Expect a refund of the remaining escrow balance within about 30 days.
Frequently asked questions
- How do I calculate my mortgage payoff date?
- Amortize the current balance at your rate and payment: each month, interest equals balance times the monthly rate, and the remainder reduces principal. The payoff month is the first month the balance reaches zero. Adding extra principal pulls that month forward.
- How much extra do I need to pay off my mortgage in 15 years instead of 30?
- Roughly the difference between the 30-year payment and the 15-year payment at the same rate. On a $450,000 loan at 6.5% that is about $1,075 more per month, and it cuts total interest by more than half.
- Is paying off a mortgage early worth it?
- Paying early earns a guaranteed, tax-free return equal to your mortgage rate. It wins when the rate is high relative to safe investment yields, when you no longer itemize deductions, or when you value the certainty. Investing can win when the rate is low and you have unused tax-advantaged space.
- Does a payoff quote match my current balance?
- No. A lender payoff quote adds interest accrued to the payoff date plus any recording or wire fees, so it is slightly higher than the statement balance. Always request an official quote before sending a final payment.
- Should I pay off the mortgage or invest the money?
- Compare the mortgage rate to your expected after-tax investment return. This tool reports NPV and IRR on the ownership cash flows so you can see the trade-off in one number rather than a rule of thumb.
Find your payoff date
Enter your balance, rate and extra payment — export the schedule to Excel or PDF when it looks right.
Open the calculator →