15- vs 30-Year Mortgage
Enter your loan amount and interest rate to compare a shorter and a longer term side by side — the monthly payment, the total interest, and how much more the shorter term costs each month.
Compare two terms
Loan amount to finance, from $1 through $100,000,000.
Annual interest rate applied to both terms, from 0% through 25%.
The 15-year saves $191,831.88 in interest versus the 30-year term.
- 15-year payment
- $2,531.57
- 30-year payment
- $1,798.65
- Extra per month
- $732.92
| Term | Monthly payment | Total interest |
|---|---|---|
| 15-year | $2,531.57 | $155,682.69 |
| 30-year | $1,798.65 | $347,514.57 |
The 15-year term costs $732.92 more per month but retires the balance far sooner and with far less interest.
How the two terms are compared
Each term uses the level payment that amortizes the same loan amount at the same rate over its number of months. Total interest is the sum of every payment minus the loan amount. The shorter term has a higher monthly payment but a much smaller interest total, because the balance is retired in far fewer months. The interest saved is simply the difference between the two total-interest figures.
Payment = L × r / (1 − (1 + r)−n)Total interest = Payment × n − L- L
- Loan amount
- r
- Monthly periodic rate (annual rate ÷ 12)
- n
- Number of monthly payments (term × 12)
$300,000 at 6%: 15 years vs 30 years
A $300,000 loan at 6% costs $2,531.57 a month over 15 years, with $155,682.69 in total interest. The same loan over 30 years costs $1,798.65 a month, with $347,514.57 in total interest. The 15-year term costs $732.92 more per month but saves $191,831.88 in interest overall.
This is an educational calculation based only on the values you provide. It does not look up your live loan terms, and it is not financial advice.
What this calculator assumes
- The same interest rate is applied to both terms — in practice shorter terms often carry a slightly lower rate.
- The rate stays fixed for the whole term in each scenario.
- Taxes, insurance, HOA dues, and PMI are excluded — this models principal and interest only.
- Both terms finance the identical loan amount.
- Money values are rounded to the nearest cent for display.
15- vs 30-year mortgage FAQ
Is a 15-year mortgage always better?
Not necessarily. A 15-year term saves substantial interest and builds equity faster, but the higher payment reduces monthly cash flow and flexibility. A 30-year term keeps payments lower and lets you invest or save the difference. The right choice depends on your budget, goals, and risk tolerance.
Can I get a 15-year result on a 30-year loan?
Partly. Paying extra principal on a 30-year loan shortens its term and cuts interest without locking you into the higher required payment. You keep the flexibility to drop back to the scheduled payment in a tight month.
Sources and review notes
Methodology last checked Jul 14, 2026. Formula implementation is covered by deterministic unit tests. No financial professional review is claimed yet.