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.
Interest Saved by Choosing 15-Year
$0
📐 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
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.
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.
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 $161,000. The difference: $247,000 — 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 $2,660/month — a difference of $637/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. 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: the lower rate, and — much larger — halving the number of months interest accrues.
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. 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 note.
Is There a Middle Path Between 15 and 30 Years?
Can you make a 30-year loan behave like a 20-year 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 note above retires it in under 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.
Frequently Asked Questions
Sources & Methodology
Calculations are based on the most current publicly available data from authoritative government and industry sources: