What this calculator helps you do
Estimate how a recurring extra payment changes payoff time and lifetime interest. The calculation runs entirely in your browser; SENNA Finance does not receive the values entered into this tool.
Worked example
Using the default example—current balance of $180,000, annual interest rate of 6.75%, remaining months of 240 months, extra monthly payment of $200—the calculator returns estimated payoff time of 15 years 5 months; normal monthly payment: $1,368.66; payment with extra: $1,568.66. Change the assumptions to match your own case rather than relying on the example.
Formula and calculation basis
Inputs are converted to the periodic units required by the formula. Results are calculated with full JavaScript numeric precision and rounded only for display.
How to interpret the result
The interest saving comes from reducing principal sooner. Confirm that your lender applies extra money to principal and does not charge a prepayment penalty.
Common mistakes to avoid
- Assuming extra payments are automatically applied to principal.
- Ignoring prepayment fees or product restrictions.
- Using the original term when only the current remaining balance and term are relevant.
Limits and assumptions
The model applies the same extra amount every month and assumes no penalty or payment holiday.
Outputs are estimates, not contractual quotations, regulated disclosures, tax advice, investment advice, or a substitute for professional review.
Frequently asked questions
Does one extra payment per year work the same way?
Not exactly. Timing matters. This tool models a fixed extra amount every month.
Can the loan finish before the entered term?
Yes. The schedule stops when the remaining principal is repaid.
Should I pay debt or invest instead?
That decision depends on risk, taxes, liquidity, and expected returns; the calculator only quantifies the loan effect.
Sources and reference context
External references provide educational context and do not imply endorsement of SENNA Finance.