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.

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

Sources & Methodology

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

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 $211,000 — saving $347,000. But the 15-year monthly payment is about $3,430 vs $2,660 for 30-year. The extra $770/month invested at 7% over 15 years grows to $247,000 — almost closing 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.