30-Year vs 15-Year Mortgage: The Real Numbers
The choice between a 30-year and 15-year mortgage affects how much you pay for your home by hundreds of thousands of dollars. Yet many buyers make this choice based only on the monthly payment difference, without fully understanding what that choice costs — or saves — over the loan's full life. Here's the complete picture.
The Core Numbers
Let's compare both options on a $350,000 loan — a close-to-median home price in many US markets:
| Factor | 30-Year (6.75%) | 15-Year (6.25%) |
|---|---|---|
| Monthly Payment | $2,270 | $3,002 |
| Payment Difference | — | $732 more/month |
| Total Interest Paid | $467,173 | $190,360 |
| Total Cost of Home | $817,173 | $540,360 |
| Interest Saved | — | $276,813 |
| Years to Own Free & Clear | 30 years | 15 years |
The 15-year mortgage saves nearly $277,000 in interest — almost the entire original loan amount. This is the mathematical case for the shorter term.
Why Are 15-Year Rates Lower?
Lenders charge lower rates on 15-year mortgages because shorter loans carry less risk. The lender gets their money back sooner, has less exposure to inflation, default risk, and economic shifts. The typical rate advantage is 0.5-0.75% — and on a large loan over many years, this difference compounds significantly.
The Equity Acceleration Effect
The 15-year mortgage builds equity dramatically faster — which matters if you ever need to sell, access home equity, or refinance.
| Year | 30-Year Balance | 15-Year Balance | Equity Difference |
|---|---|---|---|
| Year 5 | $322,000 | $255,000 | $67,000 |
| Year 10 | $291,000 | $177,000 | $114,000 |
| Year 15 | $248,000 | $0 (paid off!) | $248,000 |
After 15 years, the 30-year borrower still owes $248,000. The 15-year borrower owns the home completely. That difference in equity represents enormous financial security and flexibility.
The "Invest the Difference" Argument
Some financial advisors argue: take the 30-year, invest the $732/month difference, and come out ahead. The math depends on investment returns vs your mortgage rate.
- At 7% investment returns vs 6.75% mortgage rate: investing wins — barely
- At 6% returns vs 6.75% rate: 15-year mortgage wins
- The 15-year offers a guaranteed equivalent return equal to your interest rate — risk-free
In theory, investing the difference wins. In practice, most people don't consistently invest the difference for 30 years with the same discipline as making a required mortgage payment. The 15-year forces the savings automatically.
Retirement Planning Implications
If you're 40 years old and take a 30-year mortgage, you'll be 70 when the loan is paid off — well into retirement. With a 15-year, you're mortgage-free at 55, giving 10+ years of no housing payment to supercharge retirement savings. This timing advantage can be worth more than the mathematical interest savings.
Who Should Choose the 30-Year
- The 15-year payment is genuinely unaffordable or creates stress
- You have other high-interest debt to pay first
- Your income is variable and you want flexibility in tight months
- You're early in career with income expected to grow significantly
- You want to maximize contributions to tax-advantaged retirement accounts first
Who Should Choose the 15-Year
- The higher payment is comfortable — not a stretch
- You're in your 40s-50s and want to be mortgage-free before retirement
- You have stable, predictable income
- You've already maxed retirement accounts
- You value the psychological freedom of debt-free homeownership sooner
The Middle Path: 30-Year With Extra Payments
A smart hybrid: take the 30-year mortgage for payment flexibility, but make extra principal payments equivalent to a 15-year payment whenever possible. You get the lower required payment of a 30-year (protection during financial difficulty) while capturing much of the interest savings when you make extra payments. The downside: you don't get the lower interest rate of a true 15-year.
Compare Your Payment Options
Use our mortgage calculator to see the exact difference for your loan amount and situation.
Calculate →The Bottom Line
The 15-year mortgage wins on mathematics by a massive margin. But financial decisions aren't purely mathematical — they must account for cash flow, income stability, other financial goals, and life unpredictability. Choose the 15-year if you can comfortably afford it. Choose the 30-year if you can't — but commit to making extra payments consistently. Either way, understanding the difference helps you make an informed decision.