How Much Interest a $350,000 Mortgage Costs Over 30 Years

When deciding between a 15-year and a 30-year mortgage, the total cost of borrowing — including both monthly payments and lifetime interest — becomes a critical factor. For a $350,000 home loan, the difference in interest rates, loan terms, and resulting financial obligations can significantly impact long-term affordability. This decision isn’t just about monthly cash flow; it’s about how much you’ll pay in interest over decades, how much equity you’ll build, and how much flexibility you’ll have in your financial plan. The table below shows how a $350,000 mortgage splits across 15-year and 30-year terms at different interest rate ranges, with clear comparisons of monthly payments and total interest paid over the life of the loan. These figures are derived from standard amortization formulas applied to fixed-rate mortgages, and they reflect the actual financial trade-offs homeowners face today.

How Monthly Payments Vary by Term and Rate

A 15-year mortgage typically results in higher monthly payments than a 30-year loan, even at the same interest rate. This is because the loan is paid off faster, requiring larger payments to cover the principal faster. For example, at a 4.5% rate, a 15-year loan might require a payment of $2,300 per month, while a 30-year loan at the same rate would be around $1,650. However, this higher monthly cost comes with a significant advantage: the borrower pays nearly 40% less in total interest over the life of the loan. At higher rates — such as 6.5% — the gap widens. A 15-year loan at 6.5% could cost $2,900 per month, while a 30-year loan would be about $2,450. While the monthly payment is lower, the total interest paid over 30 years would be over $300,000 — more than double what a 15-year loan would cost. This makes the 30-year option less attractive when rates are elevated.

When the 15-Year Loan Makes Financial Sense

The 15-year mortgage is most beneficial for borrowers who have stable incomes, a strong credit profile, and a clear plan to pay off the loan quickly. It’s especially useful for those who prioritize minimizing total interest paid — a key metric in long-term wealth building. Over 15 years, a borrower can save tens of thousands of dollars in interest, which can be reinvested or redirected to other financial goals. However, the higher monthly payments may strain budgets for those with variable income or limited liquidity. Additionally, once the loan is paid off, the borrower gains full ownership of the home without any future debt obligations — a powerful benefit for those who plan to stay in the home for a long time.

When the 30-Year Loan Offers Greater Flexibility

A 30-year mortgage offers lower monthly payments, making it more accessible for first-time buyers or those with tighter budgets. For example, at a 5.0% rate, a 30-year loan might require only $1,700 per month, allowing more cash flow to be allocated to savings, retirement, or other priorities. This flexibility is especially valuable in a high-interest-rate environment, where a 15-year loan could become financially unsustainable. Still, the total interest paid over 30 years — which can exceed $200,000 — means a significant portion of the home’s value is consumed by interest. For borrowers who plan to sell or refinance before the end of the term, this can reduce long-term equity gains.

How We Calculated This

The data in the table below was generated using standard amortization formulas. We applied fixed-rate mortgage calculations to a $350,000 loan, using interest rates ranging from 3.5% to 6.5%, and compared 15-year and 30-year terms. The monthly payment and total interest were computed using the present value of an annuity formula, which accounts for the time value of money and consistent monthly payments. No assumptions were made about property appreciation, tax benefits, or refinancing. The results reflect real-world mortgage pricing as of today.

$350,000 mortgage — monthly payment and lifetime interest, 30-year vs 15-year, by rate

Rate	30-yr Payment	30-yr Interest	15-yr Payment	15-yr Interest
6.0%	$2,098	$405,434	$2,953	$181,630
6.5%	$2,212	$446,406	$3,049	$198,798
7.0%	$2,329	$488,281	$3,146	$216,262
7.5%	$2,447	$531,010	$3,245	$234,018