15-Year vs. 30-Year Mortgage in 2026: The Real 10-Year Numbers, Including What You'd Need to Earn Investing the Difference

Correction October 26, 2026: an earlier version attributed the 15-year loan’s faster principal paydown to its lower rate, and described the 2010-2021 gap between 30-year and 15-year rates as smaller than today’s. The paydown gap is almost entirely a function of the 15-year term, recomputed here on this article’s own $400,000 example, and the 30-year-minus-15-year spread has sat both above and below today’s 0.69 points within the past year. Source: Freddie Mac Primary Mortgage Market Survey.

As of September 17, 2026, Freddie Mac's Primary Mortgage Market Survey puts the average 30-year fixed rate at 6.95% and the average 15-year fixed rate at 6.26%. The standard personal-finance advice for decades has been: take the 30-year loan for the lower payment, then invest the difference — you'll come out ahead because stocks have historically returned more than a mortgage costs. That advice is a real trade-off, not a rule, and at today's rate level the math is closer than most people assume. Below is the actual 10-year comparison on a $400,000 loan, run both ways, with the assumptions shown so you can rerun it with your own numbers.

Single-family American-style house exterior with front lawn
A single-family house in the United States (illustration). Photo: Ryan Hagerty / public-domain-image.com, public domain, Wikimedia Commons.

Key takeaways

  • On a $400,000 loan at Freddie Mac’s week-of-September-17-2026 averages — 6.95% for 30 years, 6.26% for 15 — the 15-year payment is $3,431.87 against $2,647.79, a difference of $784.08 a month.
  • After 10 years the 15-year borrower has paid down $223,590 of principal against $57,155, about four times as much equity, and paid $72,345 less interest.
  • Investing that $784.08 every month leaves the 30-year path $30,722 behind at a 7% return and $44,681 behind at 5%. Tying the 15-year paydown would take roughly 10.6% a year, before taxes.
  • Almost none of that gap is the rate. At the same 6.95%, a 15-year schedule still leaves about $181,200 owing, so the 0.69-point rate advantage explains only about $4,800 of the $166,435 equity gap.

Figures checked: October 26, 2026. Rates are Freddie Mac PMMS national averages for the week of September 17, 2026.

The assumptions behind every column below

Loan amount: $400,000. No discount points on either loan. Standard fully-amortizing fixed-rate schedule, no extra principal payments on either loan. Rates: 6.95% for 30 years, 6.26% for 15 years (Freddie Mac PMMS, week of September 17, 2026 — a year earlier, in September 2025, the same survey had the 30-year at 6.26% and the 15-year at 5.41%, so both loans are meaningfully more expensive than they were a year ago). Comparison horizon: 10 years, not the full loan term, because most homeowners sell, refinance, or move well before 30 years. Investment assumption for the "invest the difference" strategy: two scenarios, 7% and 5% annualized nominal return, compounded monthly, ignoring taxes on investment gains (a real cost that would only make the investing strategy look worse, not better).

Column one against column two: the first ten years

30-year @ 6.95%15-year @ 6.26%
Monthly principal & interest$2,647.79$3,431.87
Monthly payment difference15-year costs $784.08 more per month
Total interest paid, first 10 years$260,580$188,235
Remaining balance after 10 years$342,845$176,410
Principal paid down (home equity built) after 10 years$57,155$223,590

The 15-year loan builds nearly four times as much equity through paydown alone in the first 10 years, and costs $72,345 less in total interest over that same window. That gap is the entire case for the 15-year loan. The entire case for the 30-year loan is what you do with that extra $784.08 a month instead.

Column three: the 30-year loan plus the invested difference

If you take the 30-year loan and invest the $784.08 monthly difference in a taxable brokerage account every month for 10 years, the future value of that investment depends entirely on the return you actually earn:

Assumed annual returnValue of invested difference after 10 years30-year path total (home equity + investment)15-year path total (home equity only)Who's ahead
7% (a commonly used long-run planning assumption)$135,712$192,868$223,59015-year, by $30,722
5% (a more conservative assumption)$121,754$178,909$223,59015-year, by $44,681

At both a 7% and a 5% assumed return, the 15-year loan wins the 10-year comparison in this example — before any taxes on the investment gains, which would widen the 15-year loan's advantage further. Solving for the exact break-even point: the invest-the-difference strategy would need to earn approximately 10.6% annualized over this specific 10-year window just to tie the 15-year loan's paydown, not beat it. For reference on what a realistic range of long-run market outcomes looks like, NYU Stern's Aswath Damodaran publishes the full year-by-year historical S&P 500 return series back to 1928, which shows returns well above and well below 10.6% in most individual decades — a 10-year window landing above that figure is plausible but is not something you can assume as a baseline.

One useful property of this math: the 10.6% break-even return does not depend on the loan amount. A $200,000 loan and an $800,000 loan at the same two rates produce the identical break-even figure, because the payment difference, the equity gap, and the invested amount all scale together. That means a reader with a $250,000 mortgage or a $650,000 mortgage can use the 10.6% figure directly, without rerunning every dollar amount, as long as they are comparing the same 6.95%/6.26% rate pair over the same 10-year window. What does change with loan size is the absolute dollar stakes — a bigger loan means the same percentage gap translates into a bigger real-dollar consequence for guessing wrong.

A fourth column, to separate the term from the rate

The two columns above differ in two ways at once: a shorter term and a lower rate. Holding the rate still separates them. Running the same $400,000 loan on a 15-year schedule at the 30-year rate of 6.95% leaves roughly $181,200 owing after 10 years instead of $176,410.

Same loan, 10 years inBalance remainingPrincipal paid down
30-year at 6.95%$342,845$57,155
15-year at 6.95% (shorter term only)about $181,200about $218,800
15-year at 6.26% (the actual September 2026 rate)$176,410$223,590

Read down the third column and the split is plain: of the $166,435 equity gap, about $161,600 is the shorter term and about $4,800 is the 0.69-point rate advantage. That matters because the rate spread is the unstable part — in Freddie Mac’s survey it has sat both above and below 0.69 points within the past year alone, at 0.75 points in October 2025 and 0.64 points in the week of October 22, 2026 — while the term effect does not move at all. The advice to take the 30-year and invest the difference was built during a period, roughly 2010 through 2021, when both rates were far lower and the return needed to beat simple paydown was correspondingly lower. The framework was never wrong; the numbers you plug into it changed.

Running the same columns on your own quotes

National averages are a starting point, not a quote. The sequence below reproduces every figure above with your own numbers.

  1. Get current 30-year and 15-year quotes from at least two lenders, not just the Freddie Mac national average, since your rate depends on your credit, down payment, and loan size.
  2. Calculate the monthly principal-and-interest payment for both terms at your actual loan amount (a mortgage amortization calculator will do this; the formula is principal × monthly rate ÷ (1 − (1 + monthly rate)^−months)).
  3. Subtract to find your specific monthly payment difference.
  4. Amortize both loans out to your realistic time horizon (10 years is reasonable for most owners; use a shorter window if you expect to move sooner) and note the remaining balance on each.
  5. Compute the future value of investing your specific monthly difference at a range of return assumptions (try 4%, 7%, and 9% rather than picking just one).
  6. Compare: (home equity built under the 15-year loan) versus (home equity built under the 30-year loan, plus the investment account value) at your chosen horizon.
  7. Solve for, or estimate, the break-even annual return, and ask yourself honestly whether that return is a safe assumption or an optimistic one given your actual investment horizon and risk tolerance.

Where each column stops being true

  • Payment risk. $784.08 more per month is a real, fixed commitment. If income becomes less certain — job loss, a business downturn, a health issue — the 30-year loan's lower required payment is a form of insurance the 15-year loan doesn't offer, even if you intended to invest the difference.
  • Behavioral risk. This entire calculation assumes the full $784.08 difference actually gets invested every single month for 10 years, with no skipped months and no spent windfalls. Widely cited behavioral-finance research on saving behavior suggests many households who choose the lower payment do not consistently invest the gap; if the money is spent instead of invested, the 30-year loan simply costs more with no offsetting benefit.
  • Taxes. The comparison above ignores capital gains tax on investment growth, which would apply to the 30-year/invest strategy but not to home equity built through paydown. Including realistic tax drag would push the required break-even return above 10.6%, favoring the 15-year loan further.
  • Liquidity. Money in a brokerage account can be accessed in days. Home equity generally requires selling the home, a cash-out refinance, or a HELOC — each with its own cost and qualification requirements — to access.
  • Mortgage interest deduction. Since the 2017 tax law nearly doubled the standard deduction, most homeowners no longer itemize, which means the mortgage interest deduction that used to tilt this comparison toward the 30-year loan is irrelevant for a large share of borrowers today. Whether it applies to you depends on your specific itemized deductions and should be checked with a tax professional.
  • Rate-lock and refinancing risk cuts both ways. If rates fall meaningfully after closing, a 30-year borrower has a larger remaining balance to refinance and therefore captures more dollar benefit from a future refinance than a 15-year borrower who has already paid down more principal — but refinancing also resets the amortization clock and typically comes with closing costs of 2%-6% of the loan amount that this comparison does not include.

FAQ

Is a 15-year mortgage better than a 30-year in 2026?

On these September 2026 averages, and for a household that can comfortably absorb the higher payment, the numbers favor the 15-year loan. It finishes 10 years ahead by $30,722 against a 7% investment return and by $44,681 against 5%. The comparison turns on affordability of the payment, not on the rate gap.

How much higher is the monthly payment?

$3,431.87 a month against $2,647.79 on a $400,000 loan, a difference of $784.08. That gap is the money the invest-the-difference strategy depends on being invested every single month.

What return would I need to come out ahead by investing the difference?

About 10.6% annualized over the same 10-year window, before taxes, just to tie the 15-year paydown. Capital gains tax on the growth pushes the required return higher still. The 10.6% figure does not depend on the loan size as long as the same rate pair and 10-year window are used.

How much of the 15-year advantage comes from its lower rate?

About $4,800 of the $166,435 equity gap. The rest is the amortization schedule. Holding the rate at 6.95% and only shortening the term still leaves about $181,200 owing after 10 years against $342,845 on the 30-year.

When does the 30-year still make more sense?

When payment flexibility is worth more than paydown: a lower fixed payment if income drops, money that stays liquid within days rather than requiring a sale, cash-out refinance or HELOC, and a larger balance to refinance if rates fall. Refinancing resets the amortization clock and typically costs 2% to 6% of the loan amount, which this comparison excludes.

Does the mortgage interest deduction change the answer?

For most borrowers, less than it used to. Since the 2017 tax law nearly doubled the standard deduction, most homeowners no longer itemize, so the larger interest bill on the 30-year loan is not offset by a deduction they claim.

This article is for general educational purposes only and is not individualized financial, tax, or legal advice. Rates shown are national averages as of the date cited and will differ from the rate any individual borrower is quoted. Investment return assumptions are illustrative scenarios, not guarantees or forecasts, and all investing carries the risk of loss. Consult a licensed mortgage professional, financial advisor, or tax professional before making a decision based on this comparison.

Tip: Running the 15-year vs. 30-year comparison with your own rate and balance is much easier with a financial calculator that handles amortization. If you do choose the 30-year loan and plan to invest the difference, a budget planner helps you make sure that monthly gap actually gets invested instead of spent. (These are Amazon Associate links — we may earn a small commission on qualifying purchases.)

Sources

Related reading on this site: HELOC vs. Cash-Out Refinance in 2026 · FHA Mortgage Insurance in 2026: Break-Even Math

If you run these numbers on your own loan amount and get a different answer than this example, that's the point — the break-even return depends heavily on your specific rate spread and loan size, not just the general direction of the advice.

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