Convert 30 Year Mortgage to 15 Year Calculator

Converting a 30-year mortgage to a 15-year mortgage can significantly reduce your monthly payments and total interest paid, but it comes with higher upfront costs. Use this calculator to compare the two options and determine which is right for your financial situation.

How to Use This Calculator

Enter your current mortgage details in the calculator panel on the right. The calculator will show you:

Your current monthly payment and total interest
Your new monthly payment and total interest if you convert to 15 years
The difference in monthly payments and total interest
A comparison chart showing the payment breakdown

You can adjust the interest rate, loan amount, and current term to see how different scenarios affect your mortgage.

How the Conversion Works

When you convert a 30-year mortgage to a 15-year mortgage, you're essentially refinancing your loan to pay it off faster. The lender will:

Calculate your remaining loan balance
Issue you a new 15-year mortgage with the same interest rate
Pay off your existing mortgage

The key factors that affect your new payment are:

Your remaining loan balance
The new loan term (15 years)
The current interest rate

Mortgage Payment Formula

The monthly payment (PMT) for a mortgage is calculated using the formula:

PMT = (P × r × (1 + r)^n) / ((1 + r)^n - 1)

Where:

P = Principal loan amount
r = Monthly interest rate (annual rate / 12)
n = Number of payments (term in years × 12)

Worked Example

Let's look at an example to see how converting a 30-year mortgage to a 15-year mortgage affects your payments.

Scenario	Monthly Payment	Total Interest	Total Cost
Original 30-year mortgage	$1,200	$240,000	$1,200,000
Converted 15-year mortgage	$2,100	$180,000	$1,140,000

In this example, converting to a 15-year mortgage increases your monthly payment by $900 but reduces your total interest by $60,000 and your total cost by $60,000.

30-Year vs 15-Year Comparison

Here's a comparison of the key differences between a 30-year and 15-year mortgage:

Feature	30-Year Mortgage	15-Year Mortgage
Term	30 years	15 years
Monthly Payment	Lower	Higher
Total Interest	Higher	Lower
Total Cost	Higher	Lower
Refinancing Costs	None	Appraisal, closing costs
Risk	Lower (longer term)	Higher (shorter term)

As you can see, converting to a 15-year mortgage typically results in lower total interest and cost, but with higher monthly payments and upfront costs.

Frequently Asked Questions

Can I convert my 30-year mortgage to a 15-year mortgage?: Yes, you can refinance your 30-year mortgage to a 15-year mortgage, but you'll need to qualify for the new loan and pay closing costs.
What are the closing costs for converting to a 15-year mortgage?: Closing costs typically range from 2% to 5% of the loan amount and may include appraisal fees, title insurance, and origination fees.
Will converting to a 15-year mortgage save me money?: Yes, converting to a 15-year mortgage can save you money on total interest, but you'll pay higher monthly payments and upfront costs.
What happens if interest rates rise after I convert?: If interest rates rise, your monthly payments will increase, but you'll still pay off the loan faster than with a 30-year mortgage.
Can I convert my mortgage if I have a home equity line of credit (HELOC)?dt>: Yes, you can convert your mortgage to a 15-year term, but you'll need to pay off your HELOC first or include it in the new loan calculation.