Pay Off Mortgage vs Invest the Difference Calculator
Decide whether extra cash each month should attack your mortgage or go into investments — compared fairly at the same horizon.
How it works
Pay-off path: extra reduces principal, then the freed payment is invested to the horizon · Invest path: extra is invested every month for the full term · Both compared at the same end date
The honest way to compare is to measure both choices at the same finish line. In the pay-off path the extra clears the loan early, and once it is gone the whole payment plus the extra is invested for the years that remain. In the invest path the loan runs its full term while the extra compounds in the market the entire time. The winner turns almost entirely on whether your investment return beats your mortgage rate — a guaranteed rate you can compare directly.
Worked example
On a $250,000 balance at 6.5% with 25 years left, the payment is about $1,688. Adding $500 a month clears the loan in roughly 18 years, saving around $80,000 in interest; the freed cash then invests for the last 7 years. Investing the $500 the whole time at 7% grows steadily too — because 7% edges out 6.5%, investing usually wins by a modest margin, though paying off carries no market risk.
Frequently asked questions
Should I just compare my rate to my return?
That is the core of it: paying down a 6.5% mortgage is a guaranteed 6.5% return, while investing offers a higher but uncertain return. If your expected return clearly exceeds the rate you may come out ahead investing, but the mortgage payoff is risk-free.
Does tax change the answer?
It can. If you itemize and deduct mortgage interest, the effective rate is lower, tilting toward investing. Investment gains may also be taxed. This tool compares pre-tax figures, so adjust for your own situation.
What about the peace of mind of no mortgage?
That is real and not captured by the math. Many people value a paid-off home even when investing wins by a little, because it removes a large fixed obligation and market risk from their retirement.
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This is an educational estimate, not financial advice. Real results depend on rates, taxes, fees and market returns that no calculator can guarantee — confirm figures with your lender or a licensed advisor.