Loan Prepayment Calculator
Calculate how lump-sum prepayments or extra monthly contributions shorten your loan term and reduce total interest on personal and auto loans.
What this calculator does
The Loan Prepayment Calculator estimates your result instantly from the values you enter, using standard personal loans formulas. Calculate how lump-sum prepayments or extra monthly contributions shorten your loan term and reduce total interest on personal and auto loans. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate for planning rather than financial advice.
About Loan Prepayment Calculator
The Loan Prepayment Calculator calculates how making one-time or recurring prepayments directly against loan principal reduces your remaining tenure and total interest paid.
Formula & Mathematical Calculation
New Payoff Months = - [ ln(1 - (Remaining Principal × r) / (EMI + Extra Payment)) ] / ln(1 + r)
Interest Savings = Original Total Interest - New Total Interest
Calculation Example
$25,000 Loan @ 9.0% (5 Years, EMI = $518.96/mo): Adding $100/month extra pays off the loan 13 Months Early and saves $1,348 in interest.
Key Benefits
- Calculates exact months saved on any installment loan
- Supports recurring extra monthly payments or one-time lump-sum payoffs
- Shows exact dollar savings on interest charges
- Helps compare prepaying debt vs. investing extra cash
- 100% free personal finance tool
How to Use this Calculator
-
Enter Current Loan Details
Input principal balance, interest rate, and remaining months. -
Specify Prepayment Amount
Enter extra monthly payment or one-time lump sum. -
Calculate Payoff Timeline
Click Calculate to view shortened loan duration and interest savings.
Assumptions & Limitations
What the calculation assumes
- Every value you enter is treated as an exact, known amount.
- Rates and contributions are assumed to stay constant for the whole period unless the form asks for them separately.
- Results use standard financial formulas and ignore fees, penalties and promotional terms that are not entered above.
- Inflation, tax changes and market volatility are not modelled unless a field for them is provided.
- Amounts are unit-agnostic: results are returned in the same currency you enter.
What it does not cover
- Loan Prepayment Calculator produces estimates for education and planning, not a quote, offer or professional advice.
- Real-world outcomes differ when fees, taxes, rounding rules or provider-specific terms apply.
- Local regulations and tax rules vary by country and change over time; verify current rules for your jurisdiction.
- Figures are only as accurate as the inputs you supply — check them before acting on the result.
- For decisions with lasting financial impact, confirm the numbers with a qualified professional.