Quick guide
Estimate Loan Payments, Amortization and Extra-Payment Savings
Enter the amount, annual rate and term to estimate reducing-balance or flat-rate payments. Review total interest and payoff date, compare how monthly extra payments change interest and duration, and view or download a locally generated CSV amortization schedule.
What this tool does
- Estimate both reducing-balance and flat-rate loans with their difference explained before comparison.
- See the payment, total interest, total paid, payoff date and a schedule separating principal from interest.
- Compare reducing-balance extra payments by both estimated interest saved and months removed.
- Calculate up to 600 payments and create the CSV in your browser without sending financial inputs to the VPS.
How to use Loan Calculator
- 1Choose the home, car or personal example, or enter the amount, rate, term and first payment date.
- 2Choose the interest method, review the assumptions, then add fees or an extra payment when the agreement allows it.
- 3Calculate and review the summary, chart and schedule, then confirm rates, penalties and terms with the lender.
Frequently asked questions
Will this estimate match every lender?
Not necessarily. This monthly estimate assumes a fixed rate and on-time payments. A real agreement may use daily interest, variable rates, fees, insurance, taxes or different settlement rules.
How does a flat rate differ from a reducing-balance rate?
Flat interest is calculated on the original principal for the full term, while reducing-balance interest is charged on the outstanding amount. The stated percentages are therefore not directly comparable.
Does every extra payment reduce interest?
The tool assumes each extra reducing-balance payment is applied to principal on the due date with no penalty. A real lender may treat it as an advance installment, limit prepayments or charge an early-settlement fee, so check the agreement.
How are fees treated?
Entered fees are added only to the total paid. They are not added to principal, charged interest or used to calculate an effective interest rate.
Are my loan details sent to the VPS?
No. Calculations, charts, the schedule, copying and CSV generation run in your browser. The VPS only serves the page and scripts; it does not receive or store the amount, rate or result.
Reference for reducing-balance loan interest: Bank of Thailand — Reducing-balance loan interest