What is Mortgage Payoff Calculator?
A mortgage payoff calculator quantifies the substantial interest savings and accelerated debt-free date achieved by applying additional cash directly toward principal reduction.
How to Use This Calculator
- Enter remaining principal balance and current interest rate.
- Specify how many years remain on the mortgage.
- Input your planned extra monthly or annual principal contribution.
- Discover how many years earlier your home will be completely paid off.
The Mathematical Formula & Variables
n = -ln(1 - (r * P)/(PMT + Extra)) / ln(1 + r)
Variables Definition
| Symbol / Variable | Name | Description |
|---|---|---|
n_{new} |
Shortened Periods | Number of monthly payments with extra principal added. |
Extra |
Additional Principal | Direct principal contribution each cycle. |
Step-by-Step Worked Example
Scenario: Adding $200/month extra to a $320,000 mortgage at 6.5% with 30 years remaining.
- Standard payment is $2,022.62/month.
- New payment with extra principal = $2,222.62/month.
- Accelerated payoff time: loan is paid off in 23 years and 8 months instead of 30 years.
- Original interest: $408,143. New interest: $323,831.
- Total saved: $408,143 - $323,831 = $84,312.
Result: You save $84,312 in interest and finish mortgage payments 6 years and 4 months sooner.
Frequently Asked Questions
Should I specify "apply to principal" when paying extra?
Yes. Always inform your mortgage servicer that extra payments should be applied directly to the principal balance, rather than prepaying future monthly interest.