Loan Repayment Calculator
This loan calculator with extra payments compares your standard schedule with overpayments to show interest saved and payoff dates.
Formula & worked example
Formula: Payment = P × r ÷ (1 − (1 + r)^−n), with r = annual rate ÷ 12 and n = months. Extra payments reduce the balance directly each month.
Example: 200,000 at 6% over 30 years: payment 1,199.10 and about 231,676 total interest. Adding 200 a month cuts the term by roughly 8 years.
Method & source: Standard fixed-rate amortisation formula. See how we test our calculators.
Next step: try mortgage payments or compound interest or savings goal.
What Is a Loan Repayment Calculator?
A loan repayment calculator works out your regular payment, the total interest you will pay and the date the loan will be cleared. It applies to mortgages, car loans, personal loans and student loans that use standard monthly amortisation.
This loan calculator with extra payments compares two schedules side by side – the standard one and one where you add an extra monthly payment or a one-off lump sum – so you can see what paying more really achieves.
How Our Loan Repayment Calculator Works
Enter the loan amount, annual interest rate and term. Add an extra payment to compare.
- Monthly payment: The fixed instalment that repays the loan over its term.
- Extra payments: A recurring monthly extra and/or a lump sum in the first month.
- Interest saved: The difference in total interest between the two schedules.
- Payoff date: When the loan ends with and without extra payments, based on your start month.
- Balance chart: How the outstanding balance falls in each scenario.
Extra amounts go directly against the principal after the month’s interest is paid, which is how most lenders apply overpayments. Check your lender’s terms for early repayment charges.
Why Comparing Repayment Options Matters
Interest is calculated on your outstanding balance, so every extra payment reduces the balance that future interest is charged on.
- See how much interest small overpayments can save.
- Find out how many months earlier you could be debt-free.
- Decide whether to overpay or invest instead.
- Budget with a clear payment amount.
- Compare loan offers with different rates and terms.
Seeing the interest saved and the new payoff date in black and white makes it far easier to decide how much extra you can commit to.
Worked walkthrough: a car loan
A 15,000 car loan at 7.9% over five years has a monthly payment of about 303.43 and costs roughly 3,205.71 in interest over 60 months. If you add 50 a month, the loan is cleared in 50 months instead of 60, ten months early, and total interest falls to about 2,649.48 – a saving of 556.23. A one-off lump sum in month one has a similar effect. The balance chart shows the two schedules side by side, and the results list the payoff month for each, based on the first payment month you choose.
Practical tips for loan repayment calculations
- Check whether your lender allows overpayments without a fee, and whether extra money reduces the balance or just prepays future instalments.
- The earlier you overpay, the more interest you save, because interest is charged on the outstanding balance.
- Compare loans by total cost, not just monthly payment. A lower payment over a longer term usually means more interest overall.
- This calculator covers principal and interest only. Arrangement fees, insurance and early-repayment charges are not included.
- Rates can change on variable loans. Re-run the numbers when your rate changes to keep the schedule realistic.
Frequently Asked Questions (FAQs)
Enter the loan amount, the annual interest rate and the term. The calculator uses the standard amortisation formula to give a fixed monthly payment.
Extra payments lower the balance sooner. Since interest is charged on the remaining balance, less interest accrues in every later month.
Yes. Enter it in the lump sum field. It is applied in the first month on top of your regular payment.
No. It covers principal and interest only. Fees, insurance, taxes and early repayment charges are not included.
The calculator adds the number of months needed to your chosen start month. With extra payments, the loan ends sooner and the new date is shown next to the original.
Estimates only – not financial advice. Results assume a constant interest rate, regular payments and no fees, taxes or inflation unless stated. Real accounts and loans differ, and past or assumed returns are not guaranteed. This tool is not financial or investment advice; check your own account or loan terms and speak to a qualified adviser. See our full disclaimer.