Build the repayment schedule period by period — principal, interest and the remaining balance — with the interest methods and rate phases common in bank loan contracts.
Equal principal and equal instalments are both called "reducing balance", but they produce different schedules: with equal principal the first payment is the largest and payments shrink; with equal instalments each payment is roughly the same. The tool calculates each one separately.
Contracts often offer a teaser rate for a few years, then float. When the teaser ends, payments can rise noticeably if the rate moves higher. The tool accepts several rate phases.
With flat interest, interest is charged on the original amount for the whole term even as the balance falls. The tool converts it to the equivalent rate on a reducing balance so you can compare.
The loan amount (for a loan already running, the balance left), the years left to pay, the interest method, and each rate phase.
Principal grace (interest only) or interest grace (interest added to the balance). With interest grace the balance after the grace period is larger than the amount borrowed, and the tool shows by how much.
The first payment, the largest payment, total interest, total repaid, the effective rate, and the full schedule — exportable to CSV to check against the bank’s own table.
One made-up scenario: what the tool returns, and how to read it.
These are illustrative figures, not anyone’s real data. The assumptions are set deliberately high so they match no one’s situation, and are calculated with the app’s own formulas to show how to read the results.
This is not financial advice, nor an offer to lend or invest. To work out your own situation, use the tool in the app.
A few of 240 periods. Highlighted: the first period after the teaser rate ends.
| Period | Rate / year | Opening balance | Principal | Interest | Payment | Closing balance |
|---|---|---|---|---|---|---|
| 1 | 6.9% | 48,800,000,000 ₫ | 203,333,333 ₫ | 280,600,000 ₫ | 483,933,333 ₫ | 48,596,666,667 ₫ |
| 2 | 6.9% | 48,596,666,667 ₫ | 203,333,333 ₫ | 279,430,833 ₫ | 482,764,167 ₫ | 48,393,333,333 ₫ |
| 3 | 6.9% | 48,393,333,333 ₫ | 203,333,333 ₫ | 278,261,667 ₫ | 481,595,000 ₫ | 48,190,000,000 ₫ |
| … | ||||||
| 35 | 6.9% | 41,886,666,667 ₫ | 203,333,333 ₫ | 240,848,333 ₫ | 444,181,667 ₫ | 41,683,333,333 ₫ |
| 36 | 6.9% | 41,683,333,333 ₫ | 203,333,333 ₫ | 239,679,167 ₫ | 443,012,500 ₫ | 41,480,000,000 ₫ |
| 37 | 14.6% | 41,480,000,000 ₫ | 203,333,333 ₫ | 504,673,333 ₫ | 708,006,667 ₫ | 41,276,666,667 ₫ |
| 38 | 14.6% | 41,276,666,667 ₫ | 203,333,333 ₫ | 502,199,444 ₫ | 705,532,778 ₫ | 41,073,333,333 ₫ |
| … | ||||||
| 120 | 14.6% | 24,603,333,333 ₫ | 203,333,333 ₫ | 299,340,556 ₫ | 502,673,889 ₫ | 24,400,000,000 ₫ |
| … | ||||||
| 239 | 14.6% | 406,666,667 ₫ | 203,333,333 ₫ | 4,947,778 ₫ | 208,281,111 ₫ | 203,333,333 ₫ |
| 240 | 14.6% | 203,333,333 ₫ | 203,333,333 ₫ | 2,473,889 ₫ | 205,807,222 ₫ | 0 ₫ |
Swipe sideways to see the whole table.
The effective rate is measured on what you actually still owe over time.
| Method | First payment | Largest payment | Total interest | Effective rate |
|---|---|---|---|---|
| Equal principal, interest on the falling balance | 483,933,333 ₫ | 708,006,667 ₫ | 61,094,041,667 ₫ | 11.21% a year |
| Equal instalments | 375,422,207 ₫ | 598,512,325 ₫ | 86,811,713,662 ₫ | 11.66% a year |
| Flat rate (on the original amount) | 483,933,333 ₫ | 797,066,667 ₫ | 131,223,200,000 ₫ | 15.86% a year |
Swipe sideways to see the whole table.
In the app you can change every assumption and see the result update right away.
