About the 15 vs 30 Year Mortgage Calculator
This calculator puts a 15-year and a 30-year fixed-rate mortgage side by side for the same home and down payment. Enter the price, what you will put down and the rate a lender quotes for each term, and it shows both monthly principal-and-interest payments, the extra you would pay each month on the shorter loan, and the total interest each loan costs over its life.
It is useful for buyers who can afford a higher payment and want to know whether the savings are worth it, and for homeowners deciding whether to refinance into a shorter term. Because 15-year loans are usually priced lower than 30-year loans, the calculator lets you enter a separate rate for each term rather than assuming they are the same.
Figures cover principal and interest only; property tax, insurance and PMI are the same for either term and are left out so the comparison stays clean. The chart shows how much faster the 15-year balance falls, which is also how quickly you build equity.
With the default inputs, the interest saved with 15 years is $261,123.47. Change any value above to recalculate instantly.
How to use the 15 vs 30 year mortgage calculator
- 1Enter the home price and your down payment.
- 2Enter the 30-year rate you have been quoted.
- 3Enter the 15-year rate — usually a little lower than the 30-year rate.
- 4Compare the two monthly payments and the extra you would pay each month.
- 5Check the interest saved and the balance chart to judge whether the higher payment is worth it.
Formula and method
Both payments use the standard fixed-rate amortization formula. P is the loan amount (home price minus down payment), r is the monthly rate (annual rate ÷ 12) and n is the number of monthly payments: 180 for 15 years and 360 for 30 years.
Total interest is the sum of the interest charged each month as the balance is paid down, which equals M × n − P. Interest saved is the 30-year total interest minus the 15-year total interest. Taxes, insurance and PMI are excluded because they do not depend on the loan term.
- M
- Monthly principal and interest payment
- P
- Loan amount
- r
- Monthly interest rate (annual rate ÷ 12 ÷ 100)
- n
- Number of monthly payments (180 or 360)
Worked examples
$400k home, $80k down, 6.75% vs 6%
On a $320,000 loan the 30-year payment at 6.75% is $2,075.51 and the 15-year payment at 6% is $2,700.34 — about $625 more each month. In exchange, total interest falls from roughly $427,185 to $166,062, a saving of about $261,123.
$250k loan, same 6.5% rate for both terms
Even at the same 6.5% rate, the shorter term saves about $176,863 on a $250,000 loan simply because interest runs for half as long. The 15-year payment is $2,177.77 versus $1,580.17.
$500k loan, 7% vs 6.25%
For a $500,000 loan the 15-year payment is $4,287.11 versus $3,326.51 for 30 years, so choosing 15 years adds about $961 a month to the budget.
Frequently asked questions
Is a 15-year mortgage better than a 30-year mortgage?+
A 15-year mortgage costs far less interest and builds equity much faster, but the monthly payment is roughly 30–40% higher at typical rate gaps. It is better if the payment fits comfortably with room for savings and emergencies; otherwise a 30-year loan offers flexibility.
Why are 15-year mortgage rates lower?+
Lenders take less interest-rate and credit risk when money is lent for a shorter period, so 15-year fixed rates are usually around half a percentage point to three-quarters of a point below 30-year rates.
Can I get 15-year results with a 30-year mortgage?+
Yes. Paying the 15-year payment amount on a 30-year loan pays it off in roughly 15–17 years, depending on the rate gap. You keep the option to drop back to the lower required payment, but you do not get the lower 15-year rate.
How much more is a 15-year mortgage payment?+
It depends on the rates, but for typical rates the 15-year payment is about 30–40% higher than the 30-year payment on the same loan. Enter your own quotes above to see the exact gap.
Does the loan term change PMI, taxes or insurance?+
Property tax and homeowners insurance are the same for either term. PMI rates can be slightly lower on 15-year loans and PMI ends sooner because the balance falls faster, which adds to the savings shown here.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.
Sources