30-Year vs 15-Year Mortgage
30-Year vs 15-Year Mortgage
A 30-year mortgage is cheaper per month but costs roughly double in total interest. A 15-year builds equity twice as fast but requires 30% higher monthly payments. The right choice depends on your budget, income stability, and investment discipline.
Key takeaways
- 30-year mortgages cost 40–50% lower monthly payment but 60–70% higher in total interest.
- 15-year mortgages cost 25–30% higher per month but save $150,000+ in interest on a $300,000 loan.
- Rate spread: 15-year rates are typically 0.25–0.5% lower than 30-year, partially offsetting the higher payment.
- Choosing 30-year vs 15-year depends on: income stability, other debts, investment returns, and personal risk tolerance.
- A hybrid approach (30-year with extra principal payments) often balances affordability with interest savings.
The payment premium
A $280,000 loan illustrates the trade-off:
30-year at 6%:
- Monthly P&I: $1,679
- Total paid: $604,440
- Total interest: $324,440
15-year at 5.5% (typical rate discount):
- Monthly P&I: $2,159
- Total paid: $388,620
- Total interest: $108,620
Monthly difference: $2,159 − $1,679 = $480 (28.6% higher).
Not everyone can absorb a $480/month payment increase. For a household with $5,000/month net income and other debts (car, student loans, childcare), the difference might be the margin between comfortable and stressed.
Total cost comparison: 30 vs 15
| Metric | 30-year | 15-year | Difference |
|---|---|---|---|
| Monthly payment | $1,679 | $2,159 | +$480 (28.6%) |
| Total paid over term | $604,440 | $388,620 | −$215,820 |
| Total interest | $324,440 | $108,620 | −$215,820 |
| Payoff date | 30 years | 15 years | 15 years earlier |
The 15-year saves $215,820 in interest—equivalent to $600/month in savings spread over 30 years (if you don't actually pick the 15-year).
Over the full 30-year period, the 30-year borrower pays $215,820 extra in interest just for the flexibility of lower monthly payments.
Rate differential: 30-year rates are higher
Lenders charge more for 30-year mortgages because their money is at risk longer. Inflation, default risk, and refinance risk all extend over 30 years instead of 15.
Typical spread (as of 2024):
| Term | Rate | Rate vs 30-year |
|---|---|---|
| 15-year fixed | 5.50% | −0.50% |
| 20-year fixed | 5.75% | −0.25% |
| 30-year fixed | 6.00% | Baseline |
On a $280,000 loan, this 0.5% difference is powerful:
30-year at 6.00%: $1,679/month 15-year at 5.50%: $2,159/month 15-year at 6.00% (same rate): $2,247/month
If rates were identical, the 15-year would be $88/month more expensive, not $480. The rate discount makes the 15-year more attractive but still doesn't eliminate the payment premium.
Opportunity cost: Could you invest the difference?
The case for 30-year mortgages rests on opportunity cost. If you take the 30-year and invest the $480/month difference at 7% annually:
- $480/month × 12 = $5,760/year
- 30 years compounded at 7%: $5,760 × [((1.07)^30 − 1) / 0.07] ≈ $685,000
Subtract the interest saved with a 15-year ($215,820):
- Net gain from investing the difference: $685,000 − $215,820 = $469,180
This argument suggests a 30-year is better if you have the discipline to invest the $480/month. But here's the catch: most people don't invest it. They spend it.
Who should choose 15-year?
Pick 15-year if:
- You have stable income and can afford the $480+/month premium without stress.
- You're over 40 and want to be mortgage-free before retirement.
- You dislike leverage and want to own your home outright.
- You're self-employed or freelance and want predictability and low long-term obligations.
- You'd otherwise spend the monthly difference (no investment discipline).
- You inherited money or expect a large windfall in the next 5 years.
Real-world 15-year scenario: You earn $120,000/year, have $40,000 saved, stable job, no other debt. You buy a $350,000 home with 20% down ($70,000). The 15-year payment of $2,159 + taxes/insurance/PMI = ~$2,700/month is 27% of gross income (within comfort zone). You choose 15-year because you want to own it free and clear by age 60.
Who should choose 30-year?
Pick 30-year if:
- You're under 45 and have a 35+ year income runway; you can always pay extra later or refinance.
- You have other high-priority financial goals: maxing 401(k), paying down student loans, building emergency fund.
- Your job is cyclical or uncertain (freelance, commission-based, startup).
- You want flexibility; if income drops, the lower payment keeps you afloat.
- You expect above-market investment returns and have history of investing disciplined.
Real-world 30-year scenario: You're 28, earning $80,000, with $35,000 saved. You want to buy a $300,000 home at 15% down ($45,000). The 30-year payment (~$1,450/month P&I) leaves room to max a 401(k) ($1,500/month), keep an emergency fund growing, and invest extra. You take the 30-year and commit to investing $250/month in index funds. By age 58, you've either paid off the mortgage or have $400k+ in investments to do so.
The hybrid approach: 30-year with extra principal
Most practical: Take a 30-year mortgage for budget safety, then pay extra principal when possible.
Example commitment:
- Baseline payment: $1,679/month
- Extra principal: $200/month (when possible; skip during lean months)
- Average extra over 30 years: $150/month
- Payoff: ~23 years instead of 30
- Total interest: ~$250,000 instead of $324,000
- Savings: $74,000 without the monthly burden of a 15-year
This approach trades off half the interest savings for flexibility. It's realistic because life happens—job loss, medical bills, car repairs—and the lower baseline payment provides breathing room.
Tax implications (minor in modern era)
Pre-2017, mortgage interest deduction was valuable for many filers (deducting interest from taxable income). Post-2017 Tax Cuts and Jobs Act, the standard deduction nearly doubled, so fewer people itemize, and the deduction is less valuable.
If you itemize (high income, high state taxes), mortgage interest is still deductible. A 30-year mortgage gives you more interest to deduct in early years. But this shouldn't drive your mortgage term choice—the deduction is just a modest tax break, not a financial justification for paying $215,000 extra in interest.
Refinance optionality: 30-year advantage
A 30-year mortgage is refinanceable to a 15-year when rates drop or income rises. A 15-year is refinanceable to a longer term only if you get into trouble. Refinancing is expensive ($3,000–$5,000 in costs) and makes sense only if you can save $100k+ in interest or lower payment sufficiently.
In 2020–2021, many borrowers who took 30-year mortgages in 2019–2020 at 4.5% refinanced to 3.0–3.5% (a massive refi). Had they chosen 15-year at 4.0%, they would have paid off early at higher cost and benefited less from the refi opportunity.
This argues for 30-year: optionality. If rates drop dramatically, you can refinance to 15-year and lock in the gain. If rates stay high, you keep the lower payment.
Worked example: 30-year vs 15-year with real numbers
Home: $350,000. Down payment: 20% ($70,000). Loan: $280,000.
Option A: 30-year at 6.0%
- Monthly payment: $1,679
- Year 1 budget: $1,679 + $350 tax + $120 insurance = $2,149 total
- Remaining after-tax income (assuming $100k gross, 25% tax): ~$7,500/month
- After housing: $5,351/month for all expenses, investments, savings
- 30-year total cost: $604,440
- Total interest: $324,440
Option B: 15-year at 5.5%
- Monthly payment: $2,159
- Year 1 budget: $2,159 + $350 tax + $120 insurance = $2,629 total
- Remaining income after housing: ~$4,871/month
- Tighter, but manageable if no other major debts
- 15-year total cost: $388,620
- Total interest: $108,620
Hybrid Option C: 30-year at 6.0%, pay extra $300/month principal
- Monthly commitment: $1,679 + $300 = $1,979
- Payoff: ~21 years (not 30)
- Total paid: ~$455,000
- Total interest: ~$175,000
- Interest saved vs pure 30-year: $149,440
- Interest saved vs pure 15-year: $66,380
- Flexibility: In lean years, can drop to $1,679 baseline
For the hypothetical $100k gross household, Hybrid C balances monthly affordability ($1,979 total with taxes/insurance) with meaningful interest savings.
Decision tree
Next
You've chosen your loan term. Now comes another layer of rate control: mortgage points and buydowns. You can pay upfront to lower your rate, or skip points and pay slightly higher rate for 30 years. The break-even math is crucial.