15 vs 30 Year Mortgage Calculator

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Compare 15-year and 30-year mortgages side by side: monthly payment, total interest, and how much you save by going shorter.

Quick answer: A 15-year mortgage costs less overall but demands a bigger monthly payment than a 30-year loan. On a $400,000 mortgage at 7% (30-year) versus 6.25% (15-year), the 15-year saves about $341,000 in total interest, while the monthly payment runs roughly $770 higher, per standard loan amortization math.

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🏠 15-Year Mortgage
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Total Interest: $0
Total Cost: $0
🏠 30-Year Mortgage
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Total Interest: $0
Total Cost: $0

Interest Saved by Choosing 15-Year

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📐 Formula

Monthly Payment = P × [r(1+r)^n] / [(1+r)^n − 1]. Interest Saved = (30yr total payments) − (15yr total payments)

How to use the 15 vs 30 year mortgage calculator

1

Enter the loan amount

Input the amount you need to borrow after your down payment. For a $400,000 home with 20% down, enter $320,000.

2

Set rates for each term

Enter the offered rate for each. Lenders typically price 15-year mortgages 0.5–0.75% lower than 30-year; use actual quotes rather than estimated differences.

3

Compare total interest paid

This single number, often $200,000–$300,000 more on the 30-year, is the most impactful figure in the comparison.

The real cost difference between 15 and 30 years

On a $320,000 mortgage, the total interest difference between a 15-year and 30-year loan is staggering. At 6.5% (30-year) vs 5.75% (15-year), the 30-year term pays approximately $408,000 in total interest. The 15-year pays approximately $158,000. The difference: $250,000, nearly the original loan amount paid purely in interest. This is why the 15-year mortgage is consistently recommended for those who can service the higher monthly payment.

Monthly Payment Impact: Can You Afford the 15-Year?

The monthly payment on a 15-year mortgage is typically 40–50% higher than the 30-year equivalent. On a $320,000 loan, the 30-year at 6.5% runs approximately $2,023/month; the 15-year at 5.75% runs approximately $2,657/month, a difference of $635/month. Before choosing, stress-test this number against a 20% income reduction. If the 15-year payment would become unmanageable, consider a 30-year mortgage with disciplined extra payments. This approach preserves cash flow flexibility while capturing most of the interest savings of the shorter term.

The third option: 30-year with accelerated payments

Making one extra principal payment per year on a 30-year, 6.5% mortgage shortens the loan by approximately 4–5 years and saves tens of thousands in interest. Biweekly payments (26 half-payments = 13 full payments annually) achieve similar results. Run your own numbers month by month in the Amortization Calculator to see exactly which payment retires the principal. This hybrid preserves flexibility: in a lean month, you revert to the lower required payment, while capturing most of the 15-year's interest saving in good months. This is particularly valuable for borrowers with variable income.

How to compare 15 vs 30 year mortgages by hand: worked example

Take a $400,000 loan. Fifteen-year money is priced cheaper, so assume 6.5% for the 30-year and 5.875% for the 15-year, a typical spread. Both payments come from M = P × [r(1+r)ⁿ] ÷ [(1+r)ⁿ − 1].

30-year: monthly rate 0.065 ÷ 12 = 0.005417, n = 360. M = $2,528.27. Lifetime interest: 360 × $2,528.27 − $400,000 = $510,178; you repay more in interest than you borrowed.

15-year: monthly rate 0.004896, n = 180. M = $3,348.47. Lifetime interest: $202,725.

The 15-year costs $820.20 more per month but saves $307,453 in interest and delivers a paid-off house 15 years sooner. Two forces drive the saving: a lower rate, and the far bigger factor of paying interest for half as many months.

What if you invested the $820 difference instead?

The strongest case for the 30-year: take the smaller payment and invest the $820 monthly gap. At a 7% return over 30 years that stream compounds to roughly $1,000,000, comfortably more than the interest saved, though with market risk and only if the money is actually invested every month with discipline. Model your own rate and horizon in the Compound Interest Calculator. The mortgage payoff is a guaranteed after-tax return equal to your rate; the investment route is a higher expected but uncertain return. Households that would spend the difference rather than invest it are usually better served by the forced saving of the 15-year loan.

Is there a middle path between 15 and 30 years?

Can you make a 30-year loan behave like a shorter one?

Yes, take the 30-year for its lower required payment, then voluntarily pay the 15- or 20-year amount. Paying $3,348 on the 30-year loan above retires it in about 16 years and captures most of the interest saving, while keeping the option to drop back to $2,528 during a job loss or emergency. You give up the 15-year's rate discount but buy meaningful payment flexibility; the right trade depends on how stable your income is.

Who should generally avoid the 15-year payment?

Borrowers without a funded emergency reserve, anyone not yet capturing their full employer retirement match, and buyers whose 15-year payment would exceed roughly 28% of gross income. A mortgage paid off quickly is a poor consolation for an under-funded retirement account that lost 15 years of compounding.

⚠️ Disclaimer Estimates are for informational purposes only and do not constitute financial or legal advice; actual mortgage rates and terms depend on your lender, credit profile, and loan type.

Frequently Asked Questions

Financially, yes: you pay far less interest. But the higher monthly payment may strain your budget. Many financial advisors suggest the 30-year if the monthly difference would be invested in index funds instead.
Yes, typically 0.5–0.75% lower than 30-year rates. Shorter loans are less risky for lenders. This rate advantage, combined with fewer payments, creates substantial savings.
You can pay off a 30-year mortgage in 15–20 years by adding extra principal payments monthly. This gives you the flexibility of the lower required payment with the potential to pay it off faster.
On a $400,000 mortgage at 7% (30-year) vs 6.25% (15-year): the 30-year costs approximately $558,000 in total interest; the 15-year costs approximately $217,000, saving $341,000. But the 15-year monthly payment is about $3,430 vs $2,660 for 30-year. The extra $770 a month invested at 7% over 15 years grows to about $244,000, closing most but not all of the gap.
15-year wins if: you can comfortably afford the higher payment, you prioritize debt freedom, and you're in a high tax bracket (mortgage interest deduction becomes less valuable at lower loan balances). 30-year wins if: the payment flexibility matters, you'd invest the difference consistently, or you might move within 7 years.
Ramsey recommends only the 15-year fixed mortgage and says he'd never suggest a 30-year loan. His own example: a $320,000 loan at 6% over 15 years costs about $166,000 in interest, versus $427,000 at 6.75% over 30 years, a difference of roughly $260,000. Most mortgage professionals treat this as one valid strategy rather than a rule: a 30-year loan with voluntary extra payments (see the accelerated-payment option above) captures much of that saving while keeping the lower required payment available if your income drops.
The calculation flips for a rental. Mortgage interest is a deductible business expense, and the loan is a tool for leverage rather than debt to eliminate. A 30-year loan's lower payment leaves more monthly cash flow, which many investors use to buy additional rentals instead of paying down one faster. A 15-year loan builds equity sooner and reaches positive cash flow on a single property faster, which suits an investor who values certainty over growing the portfolio. This is different from the buy-a-home-to-live-in decision above, where clearing debt is usually the priority.

Sources & Methodology

Calculations are based on the most current publicly available data from authoritative government and industry sources: