Mortgage
30-Year vs. 15-Year Mortgage: The $333,000 Cost Difference in 2026
A 15-year mortgage saves $333,000 in interest vs. a 30-year on a $400k loan at 2026 rates. Here's the full breakdown and when each term actually makes sense.
Disclaimer: Tax figures reflect estimated 2026 projections based on IRS Publication 15-T. Tax law changes frequently. Verify with a CPA or the IRS Tax Withholding Estimator. Calcwyse.com is not a tax advisor.
On a $400,000 mortgage, the 30-year loan costs $333,000 more in total interest than the 15-year at current rates. That’s not a rounding error. It’s a second home. For more on this topic, see our guide: $150,000 Mortgage at 5.5%: Monthly Payment, Amortization & Total Interest.
Most buyers anchor on the monthly payment difference. Wrong number. The real trade is cash flow today versus six figures in lifetime interest.
The $400,000 Mortgage — Side by Side
Freddie Mac PMMS benchmark rates as of April 2026: approximately 6.85% on a 30-year fixed and 6.10% on a 15-year fixed. Those aren’t identical loans. Lenders price 15-year paper lower because the shorter payoff window cuts their risk.
Here’s what that gap actually costs:
📊 $400,000 Mortgage — 30-Year vs. 15-Year, 2026 Rates
30-Year Fixed 15-Year Fixed Loan amount $400,000 $400,000 Interest rate 6.85% 6.10% Monthly P&I $2,625 $3,400 Total payments $945,000 $612,000 Total interest paid $545,000 $212,000 Interest gap –$333,000 Estimates · 30-yr rate 6.85%, 15-yr rate 6.10% · Freddie Mac PMMS, April 2026 · Principal and interest only · Excludes taxes, insurance, PMI.
The monthly difference is $775. Over 15 years, paying that extra $775 on the 15-year totals about $139,500 in additional payments. But you save $333,000 in interest. Net win for the 15-year: roughly $193,000 — purely on the math.
Quick math: 30-year total cost ~$945,000. 15-year total cost ~$612,000. Gap: $333,000 in interest saved on the shorter term. Estimated · 2026 benchmark rates · principal and interest only · standard amortization.
What the Monthly Gap Actually Buys You
The $775/month payment difference isn’t dead money on the 30-year. It’s cash flow. The question is whether you deploy it.
Say you invest that $775/month into a broad index fund at 7% annually. Over 15 years — the same window as the 15-year payoff — that’s roughly $244,000. The 30-year’s $333,000 interest penalty shrinks to a net drag of about $89,000 after investing the gap. Still a loss. But smaller.
Most people don’t invest the difference. They spend it. If that’s you, the 15-year wins decisively.
The honest version: the 15-year is better if you can afford it without strain. The 30-year makes sense only if the payment gap goes directly into a brokerage account — and stays there.
Where You Live Changes the Math
High-cost markets complicate this. A $400,000 loan in Phoenix is a starter home. In San Jose, it’s a down payment on a condo.
In markets where $400k doesn’t go far, buyers often can’t qualify for the higher 15-year payment. A nurse at Banner Health in Phoenix earning $82,000 might qualify fine. A software engineer in Austin buying a $700,000 home with a $560,000 loan — that 15-year payment hits $4,760/month. That’s 52% of gross income. Not workable.
Most people end up in 30-year mortgages not because they’re the smarter financial choice, but because they’re the only one that clears underwriting.
Estimated annual take-home on $110,000 — 6 states compared (2026):
- 🟢 Texas — $84,200 (no income tax)
- 🟢 Nevada — $83,900 (no income tax)
- 🟡 Arizona — $81,100 (2.5% flat)
- 🟡 Colorado — $79,600 (4.4% flat)
- 🟡 Virginia — $77,900 (up to 5.75%)
- 🔴 California — $74,400 (up to 9.3%)
Source: IRS Publication 15-T + state revenue depts.
A Texas buyer keeps $9,800/year more than their California counterpart. That gap alone funds most of the 15-year’s $775/month payment premium on a $400k balance.
Monthly Budget Snapshot — Phoenix, AZ
To ground this in real numbers, here’s a single buyer carrying the 15-year payment in Phoenix on an estimated $110,000 salary (approximately $6,975/month take-home in Arizona):
Rent for a one-bedroom in the Midtown Phoenix corridor runs ~$1,450/month per Zillow, April 2026. That’s 20.8% of monthly take-home — below the 30% threshold financial planners use as the standard affordability cut-off. That’s a low rent burden for a city of this size. But add the mortgage and it’s a different picture entirely.
🏙️ Monthly Budget — Phoenix, AZ · $6,975/mo take-home
Expense Est. monthly Source Mortgage P&I (15-yr, $400k at 6.10%) $3,400 Calcwyse estimate Property tax + insurance (est.) $525 AZ avg rate + Zillow, Apr 2026 Groceries (Fry’s/Kroger, Midtown) $380 Numbeo 2025 Transit (Valley Metro, monthly pass) $64 Valley Metro 2026 Phone (T-Mobile Magenta, 1 line) $80 Carrier site Utilities $185 BLS CES Total essentials $4,634 Left over $2,341 Estimates for a single buyer. Rent burden (P&I only): 48.7% of take-home.
The PITI ratio of 55%+ is well above the standard 28%-of-gross guideline. On $110k gross, that’s $2,567/month. The 15-year payment alone is $3,400. You’re carrying the mortgage because you chose the faster payoff — not because it’s comfortable.
🏠 Calcwyse Affordability Score — $110,000 Salary, Phoenix
City Rent burden Discretionary ratio vs. Local median Score /10 Phoenix, AZ 20.8% 33.6% 1.44× 7.6 Scottsdale, AZ 28.1% 24.3% 1.19× 6.4 Rent burden 40% · discretionary ratio 40% · salary vs. local median 20%. Above 7.0 = comfortable · 5.0–6.9 = tight · below 5.0 = difficult.
Phoenix median household income ~$76,500 (Census ACS 2023). Scottsdale median ~$92,400 (Census ACS 2023). Discretionary ratio calculated from standalone rent scenario, not mortgage.
Quick Answers About 30-Year vs. 15-Year Mortgages
Is the 15-year mortgage always cheaper in total interest? Yes, always — same loan amount. Lower rate plus shorter term means less time for interest to compound. On $400k at current rates, you save $333,000.
What’s the break-even if I refinance from 30 to 15 years? Closing costs typically run $3,000–$6,000. The payment jump can be $600–$900/month. Break-even on refi costs is usually 18–36 months if you’re also dropping your rate.
Can I pay off a 30-year like a 15-year by making extra payments? Yes. Adding $775/month to principal on $400k at 6.85% pays it off in roughly 18 years — saving about $220,000 in interest. Not as good as the 15-year’s $333,000 savings, but close.
Does the mortgage interest deduction change the math? Barely, for most people. The $30,000 MFJ standard deduction (IRS Rev. Proc. 2024-40) means only about 13% of filers itemize now. If you’re in the 22% bracket and do itemize, after-tax interest savings narrow by roughly $22 per $100 of deducted interest. Still favors the 15-year.
Is the lower 30-year payment safer if income is variable? Yes, meaningfully. The $775 breathing room matters if your income fluctuates. Young family, commission-based pay, high other debt — the 30-year is a reasonable hedge. You can always make extra principal payments when cash is good.
Three Moves That Add Thousands to Your Net Worth
1. Bring a larger down payment. Every dollar down is a dollar not accruing interest at 6.85%. Going from 10% to 20% down on a $500k home cuts the loan to $400k — slashing total 30-year interest by $86,000 and eliminating PMI, which typically runs $100–$200/month.
2. Refinance when rates drop 1.5% or more. A drop from 6.85% to 5.35% on a remaining $380k balance after 3 years saves about $118,000 in interest over the loan’s remaining life. Most lenders want you staying at least 5 more years post-refi to clear closing costs.
3. Make bi-weekly payments. Half your monthly amount every two weeks adds one full payment per year. On $400k at 6.85%, that shortens a 30-year to about 26 years and saves $78,000 in interest. Most servicers set this up for free.
💡 Estimated Total Interest Saved — $400,000 Loan at Current Rates
Strategy Total interest vs. 30-yr baseline 30-year, standard payments $545,000 — 30-year + bi-weekly payments $467,000 –$78,000 30-year + $775/mo extra principal $325,000 –$220,000 15-year at 6.10% $212,000 –$333,000 Estimated · Calcwyse calculation · April 2026 benchmark rates · P&I only · IRS Notice 2024-80 · IRS Rev. Proc. 2025-19
FAQ
What’s my actual bi-weekly payment on a $400,000 30-year mortgage at 6.85%? Monthly P&I is $2,625. Bi-weekly half-payment: $1,312.50. That’s 26 payments per year — one full extra payment annually. Over the loan’s life, this saves $78,000 and cuts roughly 4 years off the term. No fee to set it up with most servicers.
Is a $400,000 15-year mortgage doable on a $90,000 income? The payment at 6.10% is $3,400/month P&I — $3,900+ with taxes and insurance. On $90k gross, take-home is about $5,700/month in a moderate-tax state. That’s 68% of take-home going to housing. Lenders want under 28% of gross, which is $2,100/month. You’re 85% over that threshold. The 30-year at $2,625 P&I is the realistic fit.
What if I’m self-employed — does the loan term affect my approval odds? The term doesn’t. But qualifying income does. Lenders average your last 2 years of Schedule C net. If net was $95k in 2024 and $110k in 2025, they qualify you at $102,500 — affecting both terms equally. Self-employment tax adds 14.13% on net earnings, which surprises a lot of first-time buyers budgeting for a mortgage. Use our self-employment tax calculator to see what you actually keep.
Should I take the 15-year or max a Roth IRA first? Both, if possible. The 2026 Roth limit is $7,000 ($8,000 if 50+). Max that first — tax-free growth compounds longer than guaranteed 6.10% interest savings when your horizon is 30+ years. After maxing the Roth, put the surplus toward the shorter term. If you can’t do both, prioritize eliminating the debt if you’re within 15 years of retirement.
How does the 30-year vs. 15-year choice interact with PMI? PMI applies when you put less than 20% down — regardless of loan term. On $400k with 10% down, PMI runs $100–$175/month until you hit 20% equity. The 15-year builds equity faster: after 5 years, you’ve paid down about $85,000 on the 15-year vs. $36,000 on the 30-year. You drop PMI roughly 8 years sooner on the 15-year, saving another $10,000–$17,000 in premiums.
Check Your Exact Scenario
Every loan amount and rate combo shifts the numbers. Run yours here:
- Mortgage calculator — monthly payment and total interest at any rate and term
- Refinance calculator — break-even timeline and interest savings from switching terms or rates
- Rent vs. buy calculator — whether buying at today’s rates beats renting in your market
Methodology
Sources & Methodology
Rates and limits reflect 2026 IRS publications, SSA wage bases, and official federal guidance. Calculators use progressive federal brackets and standard deductions unless noted.