15 and 30 Year Mortgage Calculator

Choosing between a 15-year and 30-year mortgage is a major financial decision that affects your long-term budget. Our calculator helps you compare the two options by showing monthly payments, total interest paid, and the difference in costs over time.

How to Use This Calculator

Enter your home price, down payment, and interest rate to see how much you'll pay monthly and in total for both loan terms. The calculator shows:

Monthly payments for 15-year and 30-year loans
Total interest paid over the life of each loan
The difference in total payments between the two options
A comparison chart showing the payment breakdown

Use this information to decide which mortgage term works best for your financial situation.

15-Year vs. 30-Year Mortgages

Both 15-year and 30-year mortgages have advantages and disadvantages. A 15-year mortgage typically has lower monthly payments but requires larger down payments and higher interest rates. A 30-year mortgage offers lower interest rates and smaller monthly payments but costs more in total interest over time.

Key Differences

Interest Rates: 15-year mortgages usually have higher interest rates than 30-year mortgages
Monthly Payments: 15-year mortgages have lower monthly payments
Total Interest: 30-year mortgages cost more in total interest over time
Down Payment: 15-year mortgages typically require larger down payments

Comparison Table

Feature	15-Year Mortgage	30-Year Mortgage
Typical Interest Rate	Higher (often 2-3% more than 30-year)	Lower
Monthly Payments	Lower	Higher
Total Interest Paid	Lower	Higher
Down Payment Requirement	Higher (typically 20% or more)	Lower (often 3-5%)
Loan Term	15 years	30 years

How the Calculation Works

The calculator uses the standard mortgage payment formula to determine monthly payments for both loan terms:

Mortgage Payment Formula

M = P [ i(1 + i)^n ] / [ (1 + i)^n - 1 ]

Where:

M = Monthly payment
P = Principal loan amount (Home price - Down payment)
i = Monthly interest rate (Annual rate / 12)
n = Number of payments (15 years × 12 = 180 payments for 15-year, 30 years × 12 = 360 payments for 30-year)

The calculator then calculates the total interest paid by subtracting the principal from the total payments over the life of the loan.

Note: The calculator assumes no prepayment penalties or changes in interest rates. Results may vary based on your specific financial situation.

Worked Example

Let's compare a $300,000 home with a 5% down payment and a 5% annual interest rate:

15-Year Mortgage

Principal: $300,000 × 0.95 = $285,000
Monthly interest rate: 5% / 12 = 0.4167%
Number of payments: 15 × 12 = 180
Monthly payment: $2,145.32
Total payments: $2,145.32 × 180 = $386,157.60
Total interest: $386,157.60 - $285,000 = $101,157.60

30-Year Mortgage

Principal: $300,000 × 0.95 = $285,000
Monthly interest rate: 5% / 12 = 0.4167%
Number of payments: 30 × 12 = 360
Monthly payment: $1,422.41
Total payments: $1,422.41 × 360 = $511,667.60
Total interest: $511,667.60 - $285,000 = $226,667.60

In this example, the 15-year mortgage costs $185,510 less in total payments but has higher monthly payments. The 30-year mortgage costs $45,510 more in total interest but has lower monthly payments.

Frequently Asked Questions

Which mortgage term is better?: The best mortgage term depends on your financial situation. A 15-year mortgage may be better if you can afford higher payments and want to pay off the loan quickly. A 30-year mortgage may be better if you want lower monthly payments and can afford to pay more in total interest.
Can I refinance from a 15-year to a 30-year mortgage?: Yes, you can refinance from a 15-year to a 30-year mortgage, but you may face prepayment penalties or higher interest rates. Check with your lender for specific terms.
What factors affect mortgage interest rates?: Mortgage interest rates are influenced by the federal funds rate, inflation, economic conditions, and the lender's risk assessment. Rates for 15-year mortgages are typically higher than for 30-year mortgages.
Are there any fees associated with a 15-year mortgage?: Yes, 15-year mortgages may have higher origination fees, prepayment penalties, and private mortgage insurance (PMI) costs compared to 30-year mortgages. Check with your lender for specific fees.
Can I make extra payments on a 15-year mortgage?: Yes, you can make extra payments on a 15-year mortgage, but some lenders may charge prepayment penalties. Check your loan agreement for specific terms.