Loan Amortization Calculator
Calculate loan amortization (KPR, KKB, pinjol) with flat, effective, or annuity interest. Monthly breakdown, total interest, early payoff savings. IDR/USD. 100% offline.
About this tool
A focused loan amortization tool for Indonesian lending products. Pick from three interest methods: Effective / Anuitas (the standard for KPR — mortgage — where the monthly payment stays equal but the principal/interest split shifts), Flat (used by KKB — vehicle loans — and most online loans / pinjol where interest is calculated on the original principal for the whole tenor), and Annuity (equal monthly payment, simplified model). Enter principal, annual interest, and tenor in months; the tool produces a full monthly amortization table with payment, principal, interest, and remaining balance, plus a savings estimate if you add an extra monthly payment. The chart shows the principal balance and cumulative interest over the loan life, with a marker for the early payoff point. Supports IDR with shorthand formatting (jt, M, T) plus USD/SGD/MYR/EUR. Export the table as CSV for spreadsheets.
Details
- Category
- Finance & Business
- Version
- 1.0.0
- Size
- 24 KB
- Updated
- Jun 2026
Frequently Asked Questions
What is the difference between flat and effective interest?
Flat interest calculates interest on the original principal for the entire tenor: monthly interest = P * (annual rate) / 12, regardless of how much principal is left. This is what vehicle loans (KKB) and most pinjol (online loans) use, and the total interest over the loan is easy to predict. Effective (anuitas) interest calculates interest on the outstanding principal each month: as you pay down the loan, the interest portion shrinks and the principal portion grows. The monthly payment stays the same but the split changes. This is what mortgages (KPR) and most consumer loans at banks use. On a Rp 500M loan at 10% over 20 years, flat gives you a total interest of about Rp 500M, while effective gives you about Rp 632M — a big difference, which is why flat is sometimes marketed as "cheaper" even though the total cost is the same in absolute terms.
Why does my amortization table end early when I add an extra payment?
When you enter an "extra monthly payment" and a month limit, the simulation adds that amount to every payment up to that month. This pays off the principal faster, so the loan reaches zero balance before the original tenor. The tool then truncates the table at the actual payoff month and shows a "savings" banner with the number of months and total interest you saved compared to the no-extra-payment baseline. Be careful: in the flat method, the interest portion of each payment is fixed regardless of how much principal is left, so adding extra only shortens the principal portion. In the effective method, the extra goes 100% to principal, which is what you want.
Does this include fees, taxes, or insurance?
No. The tool works on principal, interest, and tenor only. It does not add admin fees, provision fees, insurance premiums, notarial fees, or any other charges that Indonesian lenders typically bundle. For KPR, ask your bank for the "effective rate" (suku bunga efektif) which already includes some of these — or compute the all-in cost yourself by adding the total fees to the principal in the input. The amortization table itself is mathematically exact for the inputs you give it, but the actual monthly debit from your account will usually be higher than the "cicilan" shown here.
Can I export the amortization table to a spreadsheet?
Yes. The "Export CSV" button downloads loan-amortization.csv with the month number, date, payment, principal, interest, and balance columns. Open it in Excel, Google Sheets, or Numbers. The currency is plain decimal (not formatted with Rp/USD prefix) so spreadsheet apps recognize it as a number. Dates are ISO 8601 (YYYY-MM-DD) so they sort correctly. The CSV starts with the row immediately following the "Calculate" press, so if you change inputs you need to re-export.
Is my loan data private?
Yes. The calculator is pure client-side JavaScript inlined in the HTML. There are no network calls, no API uploads, no analytics, no CDN. The principal, interest, and tenor you enter stay in your browser. The CSV download uses the standard browser <a download> click and writes to your local Downloads folder. You can model a proprietary or sensitive loan (e.g. your real KPR application) without any data being transmitted.