Irish Calculators
Loans & mortgages

Loan Overpayment and Early Payoff Calculator

See how extra payments change the payoff time and interest cost of a conventional amortising loan. Enter any contractual penalties separately; the calculation does not produce a lender settlement quote.

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Your numbers

€
Use the principal owed before the next interest period.
%
Monthly interest is the annual nominal rate divided by 12. This is not a fee-inclusive APR.
Your figures stay on this device.

How the calculation works

Compare a baseline loan with a planned overpayment strategy. Supply either the remaining term or a known regular payment, then model extra monthly payments, a dated-in-the-schedule lump sum and a separate charge for the change.

Each month: interest = opening balance × annual nominal rate / 12; principal paid = payment + extras − interest. Compare both schedules, then subtract entered fees.

  1. Build the baseline schedule

    Calculate the regular payment from balance, rate and term, or use the known payment to simulate repayment. Each month's interest is charged before principal is reduced.

  2. Apply the extra repayments

    Add the monthly extra and any selected lump sum within the repayment schedule. The final payment is limited to the amount needed to clear the remaining balance and interest.

  3. Compare timing and cost

    Compare baseline and revised interest, payment counts and totals. Deduct the entered fee when assessing net benefit, rather than looking at interest saved alone.

Worked example: Known payment with one per cent monthly interest

Sample inputs demonstrate the method. They are not a forecast or product offer.

At 1% monthly interest, €1,000 with a €510 payment clears through €510 then €505. Adding €100 monthly changes those payments to €610 then €404. Both take two payments, but total payments fall from €1,015 to €1,014, saving €1 interest.

Known loan information
Current monthly payment: calculate the payoff time
Loan balance (€)
1000
Annual nominal interest rate (%)
12
Current monthly payment before extras
510
Extra payment every month
100
One-off extra payment
0
One-off payment number
1
Known early repayment fees
0
Start of first interest period
2026-01-01

Expected result

Interest saved
€1.00
Months saved
0
Base monthly payment
€510.00
New total payments including fees
€1,014.00
Worked example: Twelve interest-free instalments

Sample inputs demonstrate the method. They are not a forecast or product offer.

Known loan information
Remaining term: calculate the base payment
Loan balance (€)
1200
Annual nominal interest rate (%)
0
Remaining term (months)
12
Extra payment every month
0
One-off extra payment
0
One-off payment number
1
Known early repayment fees
0
Start of first interest period
2026-01-01

Expected result

Interest saved
€0.00
Months saved
0
Base monthly payment
€100.00
Worked example: Double an interest-free payment, with a fee

Sample inputs demonstrate the method. They are not a forecast or product offer.

Known loan information
Remaining term: calculate the base payment
Loan balance (€)
1200
Annual nominal interest rate (%)
0
Remaining term (months)
12
Extra payment every month
100
One-off extra payment
0
One-off payment number
1
Known early repayment fees
25
Start of first interest period
2026-01-01

Expected result

Months saved
6
Net saving after entered fees
-€25.00
New total payments including fees
€1,225.00

Understanding your result

Extra payments may reduce interest even when both scenarios finish in the same payment month. In that case the last payment can become smaller without a whole month being removed.

The start date labels regular monthly periods; it does not calculate actual-day interest. Changing rates, lender restrictions and unentered charges are outside this scenario.

Questions you might have

Does a lower term always mean a net saving?

Interest may fall, but early repayment fees can outweigh that saving. Both figures are shown.

Can I use this for PCP or hire purchase settlement?

No. A settlement quote and the specific contract rules are needed for those products.

Choosing the right inputs

Known loan information
Choose term mode to calculate the baseline payment, or known-payment mode when the contractual payment is already available. The payment must be sufficient to reduce the debt.
Annual nominal interest rate
Enter the annual nominal rate; monthly interest uses one twelfth of it. The model does not substitute a fee-inclusive APR for the contractual interest rate.
One-off payment number
Use the payment number when the lump sum is applied. It must be relevant to the original repayment schedule, rather than a date after the baseline debt would already be cleared.
Known early repayment fees
Enter a separate charge for the overpayment strategy. It reduces the reported net saving but is not silently added to the loan principal.

Common mistakes to avoid

  • Do not enter a known payment that only covers interest and expect a finite payoff date.
  • Do not count the same lump sum within both monthly extra payments and the dedicated lump-sum field.

Assumptions to check

  • Fixed rate, end-of-month payments and no new borrowing. Contractual penalties must be supplied.

Sources and method

Read our calculation and testing approach.