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 $250,000–$350,000 more on the 30-year, depending on the loan size and rates, 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 often a good fit for borrowers who can comfortably afford the higher payment. Its edge is certain interest savings; investing the monthly difference instead can come close, but only with market risk and discipline.

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

The monthly payment on a 15-year mortgage is typically about 30% 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 about 5 to 6 years and saves roughly $90,000 in interest on a $320,000 loan. 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 how each payment splits between interest and principal. This hybrid, a 30-year loan with extra payments, keeps the lower required payment as a fallback in a lean month, which 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 × $2,528.272 (the unrounded payment) − $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, more than the $307,453 of interest saved (a longer horizon than the 15-year comparison in the FAQ). That is only half the picture, though: the 15-year borrower is payment free from year 16 and can invest the full $3,348 for the last 15 years, which compounds to about $1,061,000 at the same 7%, so the 15-year route finishes about $61,000 ahead at 7%, and the 30-year route only comes out ahead if your investment return is above roughly 7.5%, with market risk and monthly discipline throughout. 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, by choosing your own payment instead of a lender-set one. On the worked-example loan, paying $3,348 a month (the 15-year amount) on the 6.5% 30-year retires it in about 16 years with roughly $245,600 of interest, against $202,725 on the true 15-year loan and $510,178 on the scheduled 30-year. The extra $43,000 or so is the price of the higher rate, and what it buys is the option to drop back to $2,528 during a job loss or emergency.

Who should generally avoid the 15-year payment?

The 15-year payment is a poor fit for borrowers without a funded emergency reserve, for 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

On total interest paid, yes: you pay far less. But the higher monthly payment may strain your budget, and some borrowers prefer the 30-year if the monthly difference would be invested in index funds instead; that comparison depends on the return and the horizon, as the worked example above shows.
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.
Paying extra shortens the loan: the amount you add sets the payoff date, roughly 15 to 20 years depending on how much. Before relying on it, confirm the loan has no prepayment penalty and tell your servicer in writing that extra money goes to principal, since otherwise it may be held as an early payment on the next installment.
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 a 7% return over 15 years grows to about $244,000, closing most but not all of the gap. Over the full 30 years the 15-year borrower can also invest the whole payment once the loan is gone, which more than closes it: in the worked example above (a $400,000 loan at 6.5% and 5.875%, with a 7% investment return) the 15-year route ends about $61,000 ahead, and the 30-year route only wins if returns are above roughly 7.5%.
15-year wins if: you can comfortably afford the higher payment, you prioritize debt freedom, and you don't rely on the mortgage interest deduction (it is worth less as the balance falls). 30-year wins if: the payment flexibility matters, you'd invest the difference consistently, or you might move within 7 years.
Dave Ramsey's published advice is to take only a 15-year fixed-rate mortgage, and Ramsey Solutions has said he would not recommend a 30-year loan. Using illustrative rates of our own, 6% on a 15-year loan and 6.75% on a 30-year loan, on $320,000: the 15-year costs about $166,000 in interest, versus about $427,000 for the 30-year, a difference of roughly $261,000. Many borrowers 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 leaves the property debt-free years earlier, 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: