Mortgage Calculator

The two numbers that matter more than the payment

Every mortgage ad leads with the monthly payment, because it's the number that feels affordable. The two that actually describe the deal sit deeper: total interest — on a typical 30-year loan at recent rates, you pay back roughly double what you borrowed — and the payoff date, which decides how many of your working years the bank owns a slice of. This calculator surfaces both, and shows how sensitive they are to the inputs you control.

Extra payments: a guaranteed return at your rate

Add an extra amount to the inputs above and watch the green callout: every extra dollar skips the interest queue entirely and hits principal, which shrinks the balance interest is charged on for every remaining month. A few hundred a month routinely buys back 5+ years and six figures of interest.

The honest framing: paying down a 6.5% mortgage is a guaranteed 6.5% return. Investing the same money in the market might earn more — historically it often has — but "might" is the operative word, and only the payoff is certain. At a locked 3% the historical market case is strong; at 7%+ the certain return is competitive with the uncertain one. Which you prefer depends on how much you value certainty, not on arithmetic.

What the down payment buys

A bigger down payment shrinks the loan (and every payment after it), and crossing the 20% line removes PMI — a fee that protects the lender while you pay it. If you're just below 20%, the effective return on the last few thousand dollars of down payment is often the best of any dollar in the deal.

Is a mortgage good debt or bad debt?

Mostly good — and knowing why changes how hard to attack it.

"Bad" debt is high-interest and unsecured: credit cards, payday loans, buy-now-pay-later. It compounds against you fast and buys nothing that grows. "Good" debt is low-rate and secured by something that lasts or appreciates — and a mortgage is the archetype. It's usually the lowest rate you'll ever get, stretched over decades, on a home you're building equity in, and the interest may even be tax-deductible. That combination is why a mortgage sits at the benign end of every debt ranking.

The practical consequence: a mortgage usually stays out of an aggressive payoff sprint. At a low rate, extra dollars often do more invested than prepaying — the classic priority ladder puts capturing an employer match and killing high-interest debt well ahead of extra mortgage principal. That doesn't make prepaying wrong; it makes it a choice between two reasonable uses of the same dollar, one guaranteed and one probabilistic, rather than an emergency. And the math isn't the whole choice. A paid-off house is something people buy partly for how it feels — the lowest possible cost of staying put, owed to no one, untouched by markets or a lost job. That return never shows up in a calculator, and plenty of people who know the invest-instead math still choose it. Sleeping well is a real yield.

One number hygiene point: when weighing that choice, the relevant payment is principal and interest, not the full escrowed amount. Property tax and insurance get paid whether the loan exists or not — counting them inflates what "paying off the house" appears to free up.

And a boundary worth stating: good debt is still debt. The rate is what earns a mortgage its gentle treatment, not the category. A mortgage taken at a high rate, or a HELOC drifting upward on a variable rate, moves toward the urgent end of the list regardless of what secures it. The label follows the math, not the other way around.

The ranking, roughly cheapest-to-priciest: mortgage, federal student loans, auto, HELOC, personal loans, cards. Where a debt sits on that list decides how much of this page's "extra payment" experiment it deserves.

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