15-Year vs 30-Year Mortgage: The Real Numbers
On a $300,000 loan at 6.5%, a 15-year mortgage costs $2,613 a month and $170,398 in total interest, while a 30-year costs $1,896 a month and $382,633. The shorter term saves $212,235 but demands $717 more every month for 15 years — which is why affordability, not arithmetic, usually decides.
Both loans finance the same house. The choice is whether you buy certainty with monthly cash flow.
The number nobody quotes is the flexibility premium. A 30-year loan lets you pay the 15-year amount voluntarily and replicate the shorter term exactly — then stop if you lose your job. A 15-year loan makes that payment mandatory. The true price of that flexibility is only the rate discount, roughly 0.25–0.75 percentage points.
Not financial advice. This comparison is for information only. Read the full disclaimer.
Side by side on $300,000
| Measure | 15-year at 6.5% | 30-year at 6.5% |
|---|---|---|
| Monthly payment | $2,613 | $1,896 |
| Monthly difference | — | $717 less |
| Total interest | $170,398 | $382,633 |
| Interest saved by 15-year | $212,235 | — |
| Payments made | 180 | 360 |
| Balance after 5 years | $230,151 | $280,833 |
| Balance after 10 years | $133,563 | $254,328 |
| Interest paid in first 5 years | $86,951 | $94,605 |
Figures use the standard amortization formula published on our methodology page and reproduce exactly in the mortgage calculator.
The 15-year rate discount, priced
A 15-year loan usually carries a lower rate than a 30-year, because the lender takes less rate risk over a shorter horizon. Those quotes are worth real money, and they are the only genuine advantage the shorter term has that the longer term cannot imitate.
| 15-year rate | Monthly payment | Total interest | Worth vs 30-year at 6.50% |
|---|---|---|---|
| 6.50% (no discount) | $2,613 | $170,398 | $0 |
| 6.25% | $2,572 | $163,008 | $7,390 |
| 6.00% | $2,532 | $155,683 | $14,715 |
| 5.75% | $2,491 | $148,421 | $21,977 |
Because a 30-year loan paid at the 15-year payment produces an identical schedule when the rates are equal, this discount is the entire financial prize of choosing the shorter term. If the two quotes are the same rate, the flexibility argument for the 30-year term becomes dominant.
How to choose, in order
Start from the stress payment. Take the 15-year payment — $2,613 here — and ask whether you could still pay it after a 20% income drop or a six-month job loss. If the answer is no, the 30-year term with voluntary overpayments is the honest choice.
Price the discount before you commit. Ask both lenders for their 30-year and 15-year quotes side by side. If the 15-year rate is 0.5 points lower, the term is worth about $14,715 — real money, but not enough to justify a payment you cannot sustain.
Check your other debt first. If you carry a credit card at 22%, every spare dollar belongs there before it belongs in a mortgage prepayment. Clearing $5,000 of card debt saves more in a year than a year of mortgage overpayments on this loan.
Protect the emergency fund. The 15-year payment leaves $717 less room each month. Keep at least three to six months of the full housing cost in cash before locking in a payment with no slack.
Then decide, and revisit annually. Choose the 30-year, set the payment at the 15-year level by standing instruction, and reassess each year. Every extra payment bought the same 6.5% return with no penalty and no loss of flexibility.
Common mistakes
- Counting the interest saving without the cash-flow cost. Saving $212,235 sounds decisive until you notice it costs $717 a month on time, every month, with no safety valve.
- Assuming a 15-year loan builds equity proportionally faster everywhere. After five years the balance gap is $50,682 — substantial, but the 30-year borrower who overpays voluntarily reaches the same place.
- Ignoring taxes and insurance in both columns. Escrowed tax and insurance are identical for both terms; they do not change the comparison, but they do change affordability. See what escrow covers.
- Forgetting that the 30-year payment can fall. Refinancing later, when rates drop, resets the whole calculation — and a 30-year loan keeps that option open with the most headroom.
Frequently Asked Questions
Is a 15-year mortgage always better than a 30-year?
No. The 15-year term saves about $212,000 of interest on a $300,000 loan at 6.5% and usually carries a lower rate, but the payment is $717 a month higher. It is only better if that payment stays comfortable through a job loss, a medical event, or a market downturn.
Can I get 15-year results with a 30-year loan?
Almost exactly. Paying the 15-year payment of $2,613 on a 30-year loan at the same rate clears the balance in 15 years with the same $170,398 of interest. The only loss is the 15-year rate discount of roughly 0.25 to 0.75 points, worth $7,390 to $21,977.
Why is the 15-year rate lower?
The lender takes less interest-rate risk over a shorter period and the loan amortizes faster, so equity builds sooner. That lower risk is priced as a rate discount, typically 0.25 to 0.75 percentage points below the 30-year rate.
What if I invest the difference instead?
Investing the $717 monthly difference is the strongest case for the 30-year term. It only wins if the after-tax investment return beats the mortgage rate over the whole period; a guaranteed 6.5% saved is difficult to beat reliably, so the decision depends on your risk tolerance and discipline.
Sources & methodology
- Owning a Home Consumer Financial Protection Bureau
- Primary Mortgage Market Survey Freddie Mac
Every figure on this page is computed with the standard amortization formula published on our methodology page. Last reviewed .