15-Year vs. 30-Year Mortgage: The Real Cost of the Long Road

The 30-year mortgage is the default choice for American homebuyers — but it's rarely the best choice. The lower monthly payment feels like flexibility, but it comes at a staggering cost. Understanding the true price of a 30-year term can change how you shop for loans and how aggressively you pay off the one you already have.

The interest gap is enormous

On a $400,000 loan at 6.8%: a 15-year loan costs $180,000 in total interest. A 30-year loan costs $540,000 in total interest. The 30-year loan costs exactly three times as much in interest — an extra $360,000 — for the privilege of a lower monthly payment. The 15-year payment is $3,550 versus $2,612, a difference of $938 per month.

Why people choose 30 years anyway

Housing affordability. Lenders qualify borrowers based on debt-to-income ratio, and the 30-year payment fits more budgets. It's also a safety net — if income drops, the minimum payment is lower. The problem is that most people never accelerate. They pay the minimum for 30 years and absorb the full interest cost.

The middle path: get a 30, pay like a 15

If you already have a 30-year loan, you can simulate a 15-year payoff by adding the difference to principal. On the $400,000 loan, add $938 per month and you'll pay off in roughly 15 years while keeping the flexibility to drop to the minimum if needed. This is often the best of both worlds.

When 30 years actually makes sense

• Your income is variable or commission-based and you need payment flexibility
• You're in a high-appreciation market where home equity grows faster than loan balance
• You're aggressively investing the payment difference and earning more than your mortgage rate
• You plan to sell within 7 years and won't hold the loan to term
• The 15-year payment would strain your budget beyond comfort

Recovering from a 30-year choice

If you're in a 30-year loan and want out faster, the fix is extra principal. Even modest additions reshape the curve. $300 extra per month on the $400,000 loan cuts the term to 21 years and saves $194,000 in interest. You're not stuck with your original choice.

Compare your actual options

Enter your current balance, rate, and term into the Mortgage Payoff Calculator. Model your current 30-year path. Then model adding enough to match a 15-year payment. The calculator will show the exact interest savings and new payoff date. That's your recovery plan.