finance calculator
Loan Amortization with Prepayment
See how extra monthly payments shorten your loan term and cut total interest with a full amortization-style calculation.
Results
- Standard monthly payment
- $1,799
- Payoff months (standard)
- 360
- Payoff months (with extra)
- 313
- Months saved
- 47
- Total interest (standard)
- $347,515
- Total interest (with extra)
- $294,168
- Interest savings
- $53,346
How to use this calculator
- Enter the loan amount, APR, and term.
- Add an extra monthly prepayment amount (optional).
- Review the new payoff timeline, months saved, and interest saved compared to the standard schedule.
Inputs explained
- Extra monthly payment
- Additional amount applied to principal each month to shorten the loan.
- Term
- Original amortization term. Prepayments shorten this timeline.
How it works
Monthly payment is calculated from amount, rate, and term using the standard amortization formula.
We run a month-by-month amortization adding your extra payment to principal until the balance reaches zero.
Outputs show payoff time, months saved, and interest savings versus the standard schedule.
When to use it
- Compare how an extra payment changes payoff timing for mortgages, auto loans, or student loans.
- Budgeting how much extra to send monthly to hit a target payoff year.
- Showing interest savings from rounding up payments or biweekly/extra principal strategies.
Tips & cautions
- Try small extras ($25–$100) to see surprisingly large interest savings over 30 years.
- Match your lender’s rules for applying extra payments to principal.
- If rates change (ARMs), adjust the APR to model your expected average rate.
- Assumes fixed rate and consistent monthly payments; does not model ARMs or changing rates.
- Does not show a printable schedule—summaries only.
- No taxes/insurance/fees included—principal and interest focus.
Deep dive
See how extra monthly payments cut loan interest and months off your mortgage or other loan with a prepayment amortization calculator.
Enter rate, term, and extra payment to compare payoff months and interest savings versus the standard schedule.
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