ING Early Repayment Calculator: Estimate Interest Savings

An ING early repayment calculator estimates how extra payments or a lump-sum payment could change a loan’s payoff time and interest, using your balance, interest rate, scheduled payment, and extra amount. This general calculator models a fixed-rate loan with monthly payments; it is not connected to ING and cannot confirm lender-specific fees, rules, or account figures.

Formula

The calculator first estimates the number of monthly payments needed to clear the remaining balance, then compares the total paid in the two scenarios. It assumes the last payment is the same size as the regular payment, so totals are approximate where the final payment would in reality be smaller.

• Monthly rate: r = APR / 1200, converting an annual percentage rate into a monthly decimal rate.
• Months with extra payments: n = ceil(round(-ln(1 − rB / M) / ln(1 + r), 6)), where M = scheduled payment + extra monthly payment.
• Months without extra payments: use the same formula with M = scheduled payment.
• Estimated interest in either scenario: monthly payment × estimated months − balance.
• Estimated interest saved: interest without extra payments − interest with extra payments.

B is the remaining principal in dollars, APR is the annual percentage rate, r is the monthly rate, M is the monthly payment in dollars, and n is the estimated number of months. The calculation treats the APR as a nominal rate divided by 12; it does not determine whether a particular loan uses that convention.

Worked Example

Using the calculator’s defaults: a $20,000 remaining balance, 8% APR, $500 scheduled monthly payment, and $100 extra each month.

1. Convert the APR: r = 8 / 1200 = 0.0066667 per month.
2. With the extra payment, the monthly amount is M = $500 + $100 = $600. The formula gives about 37.2 months, rounded up to 38 months.
3. Without the extra payment, M is $500. The formula gives about 44.5 months, rounded up to 45 months.
4. Approximate interest with extra payments: $600 × 38 − $20,000 = $2,800.
5. Approximate interest without extra payments: $500 × 45 − $20,000 = $2,500. The formula therefore returns estimated savings of −$300.

This result illustrates an important limitation: multiplying the full scheduled payment by the rounded-up month count can overstate the total, especially when the final payment would be much smaller. In this example, the formula’s simple total-payment comparison does not produce a reliable savings estimate. Use the month results as rough estimates only; a schedule that calculates each month’s interest and adjusts the final payment is needed for a more meaningful interest comparison. The displayed output follows the specified formula, rather than a lender’s amortization schedule.

How to Use the Calculator

• Enter the current outstanding balance, not the original amount borrowed. If the lender’s payoff quote includes accrued interest or other items, distinguish those from principal where possible.
• Enter the loan’s annual APR as a percentage, such as 8 for 8%, not 0.08.
• Enter the scheduled monthly payment and the additional amount you are considering paying each month. Enter zero extra to model the scheduled-payment case.
• Compare estimated months, then treat the interest figure cautiously because the calculator rounds payoff time up to whole months and assumes full payments throughout.

The calculator models recurring extra payments, not a one-time lump sum. For a lump-sum scenario, the balance and timing must be reflected in a month-by-month calculation. A lender’s quote or loan account may use daily interest, payment dates, rounding rules, or other terms that this simple formula does not capture.

What Early Repayment Can Change

When a payment reduces principal, a loan accruing interest on its outstanding balance generally has a smaller balance on which later interest can accrue. With the payment amount and rate held constant, that can shorten the estimated payoff period. The actual effect depends on when the lender receives and applies an extra payment and whether it is credited to principal rather than treated as an advance payment of future instalments.

“Early repayment” can refer to paying more than the scheduled amount regularly, making a one-off payment, or clearing the entire balance before the scheduled end date. These are not interchangeable: a recurring extra-payment calculator does not calculate a full settlement quote. Ask the lender how to make an extra payment and how it will be allocated. Do not assume the scheduled payment will automatically fall; the loan’s terms and servicing process determine how payments are handled.

Costs, Limits, and Common Mistakes

This estimate does not include early repayment charges, administration costs, fees, accrued interest at the settlement date, taxes, insurance, or other account-specific amounts. Such charges, if applicable, can change the cash cost of paying early. The calculator also assumes a fixed rate and stable monthly payment, with no missed payments, rate changes, payment holidays, or additional borrowing.

• Using the original balance: enter the current balance for an estimate starting today.
• Entering APR as a decimal: enter 8 for 8%, because the formula divides the percentage by 1200.
• Using an unsuitable payment amount: if the payment does not cover monthly interest, the loan will not amortize under this formula; a result may be invalid.
• Reading estimates as a quote: payoff totals and timing depend on lender calculations, dates, and account terms.
• Ignoring a smaller final payment: the calculator rounds the duration up to a whole month and uses full payments in its simple interest comparison.

For a more exact comparison, obtain the current balance, a dated payoff figure, and any applicable early-repayment charges from the lender. A detailed amortization schedule should calculate interest and principal separately for each payment period and size the final payment to the amount still owed.

Frequently Asked Questions

Does this calculator belong to ING?
No. It is a general-purpose estimate and is not affiliated with or connected to ING. It does not access an account or represent the lender’s calculation.

Can I use it for a one-off lump-sum payment?
Not directly. Its extra-payment input represents an additional amount paid every month. A lump sum needs a calculation that accounts for its date and the resulting balance change.

Why can the estimated interest saved be negative?
The simple formula multiplies the full payment by a whole-month payoff estimate and assumes every payment is full-sized. That can distort totals, particularly when the final payment should be smaller. A negative result is not a dependable prediction of actual savings.

Does paying extra always reduce the loan term?
Not necessarily under every loan’s processing rules. The result assumes extra money reduces principal promptly and that the rate and regular payment remain unchanged. Check how the lender applies additional payments.

Are early repayment fees included?
No. The calculator cannot determine account-specific fees or settlement costs. Check your loan documents or ask the lender for the figures that apply to your account.

What figures should I request from the lender?
Ask for the current principal balance, the payoff amount for a specific date, how extra payments are allocated, and whether charges apply. These details help distinguish an estimate from the amount needed to settle a loan.

This result is an estimate for education, and the lender’s disclosure gives the exact figures.

Related

• Early Payment Scheme Calculator: Extra Loan Payments
• Early Payment Terms: Discounts, Dates, and Examples
• Early Payment Loan Calculator: See Your Interest Savings

in bal | Remaining loan balance | $ | 20000 | 0.01 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in pmt | Scheduled monthly payment | $ | 500 | 0.01 | 100000000
in extra | Extra monthly payment | $ | 100 | 0 | 100000000
out months | Estimated months to repay with extra payment | months | ceil(round(-ln(1 - (apr / 1200) * bal / (pmt + extra)) / ln(1 + apr / 1200), 6)) | 0
out base | Estimated months to repay without extra payment | months | ceil(round(-ln(1 - (apr / 1200) * bal / pmt) / ln(1 + apr / 1200), 6)) | 0
out saved | Estimated interest saved | $ | pmt * base - bal - ((pmt + extra) * months - bal) | 2