Home > Housing > 15-Year vs 30-Year Mortgage
See what the numbers mean. Learn how the comparison works. Leave with a wider view of the decision.
Enter one home. Because a 15-year loan finishes years earlier than a 30-year one, we compare both over the same fixed 30-year window — long enough for the 15-year loan to be paid off and its freed-up payment invested for the years remaining, so the two options are compared on equal footing.
15-Year vs 30-Year Mortgage is a decision-making model, not a mortgage calculator. It estimates the relative value of each loan term using published rate data plus clearly stated modeling assumptions.
⚠ Estimates only, not financial advice — see the note below the results for details. US only for now.
Higher monthly payment, paid off in 15 years, far less total interest.
Lower monthly payment, paid off in 30 years, much more total interest.
Estimate only — not financial, legal, or investment advice.
Why 30 years, even for the 15-year loan? It's paid off at year 15 — this window gives that freed-up payment 15 more years to be invested, so both loans are compared over equal time.
Each line already includes every adjustment above it — this isn't a list to add up. Compare using the bottom line only.
Estimates only, not financial advice. Both loans finance the same amount at 20% down by default. Total interest reflects standard fixed-rate amortization over each loan's full term. The comparison runs on a fixed 30-year window — long enough for the 15-year loan to be paid off and its freed-up payment invested for the remaining 15 years, and for the 30-year borrower to keep investing the monthly payment difference throughout. A negative number in stages 3 or 4 means the credited investment growth has grown larger than the interest cost it's offsetting — in other words, a net financial gain rather than a net cost. Property tax, homeowners insurance, and HOA fees are the same regardless of loan term, so they're intentionally left out — they wouldn't change which option is cheaper, only how much both cost in total. Closing costs, discount points, and lender fees aren't modeled either — unlike property tax and insurance, these can genuinely differ between loan offers and terms, so confirm them directly with a lender rather than assuming they're identical. This tool also doesn't model the mortgage interest deduction — since the 30-year loan carries more interest in its early years, itemizing filers could see a bigger tax benefit there, though the larger standard deduction since 2018 means fewer households itemize than before.
15-Year vs 30-Year Mortgage takes one home price and runs both loan terms through four stages to estimate the true cost of each, over a fixed 30-year window.
Both use standard fixed-rate amortization on the same financed amount. The 15-year payment is meaningfully higher — you're repaying the same principal in half the time.
The 15-year loan almost always wins here by a wide margin — a shorter term and a lower rate both cut into how much interest accrues before the loan is paid off.
While both loans are active, the 30-year borrower has extra cash each month (the payment difference) that the 15-year borrower doesn't — because it's going straight into their higher payment instead. We credit the 30-year side with the future value of investing that difference every month for 15 years.
Once the 15-year loan is paid off, that borrower can redirect their entire former payment into investing for the remaining 15 years — a much larger monthly amount than the 30-year borrower's ongoing payment difference. The 30-year borrower keeps investing the same monthly difference throughout. This stage is usually where the 15-year option pulls decisively ahead, if it hasn't already.
A few terms worth knowing before you compare — this site is built to help you see the fuller picture, not just crunch numbers.
Quick check
Think you've got these 3 terms down?
A few more angles worth exploring — the numbers above are only part of the full picture.
No. 15-Year vs 30-Year Mortgage gives a directional estimate to help you think through a decision, not a substitute for a mortgage broker or financial advisor. Your actual rate depends on your credit, lender, and loan-to-value ratio.
5.93% (15-year) and 6.55% (30-year) reflect Freddie Mac's Primary Mortgage Market Survey (PMMS), the most widely cited source for average US mortgage rates, for the week of July 16, 2026. These rates assume a conventional, conforming loan with 20% down and excellent credit — actual quotes vary by lender and borrower profile.
It almost always wins on total interest paid, but the "invest the difference" argument says a 30-year borrower could take the money they're not putting toward a bigger payment and invest it instead. If that investment consistently earns a high enough return, the 30-year path can come out ahead in total real terms — try raising the investment return assumption to see how high it needs to go.
Thirty years is long enough for the 15-year loan to be fully paid off (freeing up its payment to invest for the remaining 15 years) while staying within the 30-year loan's own full term — putting both paths on the same time horizon for a fair comparison.
Those costs are identical no matter which loan term you choose, since you're buying the same home either way. Including them would raise both totals by the same amount without changing which option is cheaper or by how much, so they're left out to keep the comparison focused on what actually differs.
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Rate data: week of July 16, 2026 (Freddie Mac PMMS)