Mortgage Amortization Calculator (Singapore, 2026)

Using the calculator step by step

Use this to see your mortgage payment schedule: monthly payment, interest vs principal split, and remaining balance over time.

1. Enter loan amount, interest rate, and tenure.
2. Use the schedule to plan refinancing checkpoints (e.g. year 2–3).
3. Compare scenarios (rate up/down, extra payments).

Scenario library (sanity checks)

Use these simplified scenarios as sanity checks. Replace the numbers with your own situation.

• Example A (baseline):

  Loan: $600,000. Tenure: 25 years. Rate: 3.5% p.a. Review total interest and how fast the balance falls in the first 5 years.

• Example B (rate stress):

  Same loan and tenure, but rate: 4.5% p.a. Compare monthly payment and total interest to understand rate sensitivity.

Methodology & assumptions

Inputs explained

• Loan amount: the principal you borrow from the bank (exclude downpayment and fees).
• Interest rate (% p.a.): the annual rate. For floating loans, this changes over time — use a conservative stress‑test rate for planning.
• Loan tenure (years): how long you take to repay. Longer tenure lowers monthly payment but increases total interest.
• Extra payments (if any): optional lumpsum or monthly top‑ups that reduce principal faster (check your loan terms for penalties).

How to interpret the results

• Monthly payment: what you pay each month under the current assumptions.
• Total interest: total interest paid over the full tenure (this is what tenure and rate mainly drive).
• Amortization schedule: early years are interest‑heavy; later years shift toward principal repayment.
• Break‑even comparisons: use this schedule alongside refinance/reprice tools to see if fees are worth it.

Common mistakes

• Using today’s teaser rate without stress‑testing (rates can change).
• Ignoring lock‑in/clawback or partial prepayment penalties when planning extra payments.
• Comparing monthly installment only, without checking total interest over tenure.
• Forgetting other housing costs (insurance, maintenance, taxes) when budgeting affordability.
• Standard amortisation schedule (reducing balance).
• Excludes bank fees, lock-in clawbacks, legal subsidies, and partial prepayment penalties.
• Use as a planning model; confirm with your bank’s loan package.

Those are the questions that turn a mortgage schedule into a decision tool instead of a spreadsheet curiosity.

• How much interest do I still have left if I hold the loan for only 5 years?
• What balance remains if I need to sell sooner than planned?
• How much monthly payment changes when tenure is shortened?
• What is the rough interest saving from paying down principal early?

Useful planning questions this calculator can answer

The schedule is only as good as the assumptions you feed into it. If your mortgage is floating, the “amortization” line is not a promise — it is a projection under a chosen rate. If you know the rate is likely to reprice, treat this page as a baseline rather than a forecast. The same applies to partial prepayments: if you might prepay but are not sure when, run a few scenarios instead of relying on a single schedule.

When the output can mislead you

Use the summary table as a planning layer, not just a curiosity. It tells you what your balance and interest profile look like at milestones that matter for refinancing, selling, or partial prepayment. That makes it a practical tool for both owner-occupiers and investors.

The amortization schedule is most useful when you use it to answer real planning questions: “How much principal have I actually paid after 3 years?”, “What balance remains if I refinance in year 4?”, and “How much total interest do I avoid if I prepay?”. Most people look only at the monthly instalment, but the real value of the schedule is that it shows how slowly principal declines early on and how your interest burden changes across the life of the loan.

How to use the schedule properly

Before acting on the result, ask whether the output still makes sense after a conservative stress test. Good calculator use is not about precision to the last dollar; it is about avoiding decisions that only work in the optimistic case. If the answer still holds after you use harsher assumptions, that is usually a sign the decision is robust enough to move forward.

Output checklist

Re-run the calculator whenever one of the major assumptions changes meaningfully: rate, tenure, resale value, rent, energy cost, or your expected holding period. Small updates to these inputs often matter more than trying to make the original run more precise.

When to re-run the model

Use the model to see which assumptions matter most. Then spend your energy validating those assumptions rather than polishing less important inputs.

Even a good calculator cannot fully price convenience, stress, optionality, or the value of keeping your finances simple. That is why the best use of a tool like this is to narrow the range of sensible choices, not to pretend it can replace judgement. When the result is close, qualitative factors deserve more weight.

What the calculator cannot decide for you

Use the model to see which assumptions matter most. Then spend your energy validating those assumptions rather than polishing less important inputs.

Even a good calculator cannot fully price convenience, stress, optionality, or the value of keeping your finances simple. That is why the best use of a tool like this is to narrow the range of sensible choices, not to pretend it can replace judgement. When the result is close, qualitative factors deserve more weight.

What the model leaves out

• Reading one “base case” as a certainty.
• Forgetting fees, taxes, or frictional costs that sit outside the neat formula.
• Using unrealistic tenure or holding-period assumptions.
• Comparing options that are not truly substitutes.

Common interpretation mistakes

• Reading one “base case” as a certainty.
• Forgetting fees, taxes, or frictional costs that sit outside the neat formula.
• Using unrealistic tenure or holding-period assumptions.
• Comparing options that are not truly substitutes.

Mistakes to avoid when reading the output

Run one optimistic case, one conservative case, and one “messy real life” case. The messy case is the most useful: slightly worse rates, slightly lower resale, slightly higher costs, and a shorter holding period than planned. If the decision still looks acceptable, you have a more resilient answer.

Quick scenario ideas

These examples make the amortisation schedule more useful as a planning tool.

• Early-year shock: look at how much of your payment is still interest-heavy in the first few years, especially if you may move, refinance, or prepay before the loan matures.
• Partial prepayment mid-loan: test what happens if you inject a lump sum later. This shows whether the benefit is meaningful enough to justify using spare cash that way.
• Budget-first household: compare different tenures using the same property price to see whether the “comfortable” payment today quietly increases long-run interest too much.

References

• MAS

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