Mortgage Amortisation Calculator Singapore: Schedule and Prepayments
Build a reducing-balance mortgage schedule at a constant scenario rate. Extra monthly and one-off repayments reduce principal after that month’s interest. The calculation assumes the lender permits them without penalty; check your actual terms.
Results
Repayment schedule
| Year (months covered) | Interest | Principal repaid | Closing balance |
|---|
Worked example matching the defaults
S$600,000 at 3.5% over 25 years gives a S$3,003.74 base monthly payment. With no extras, total interest is S$301,122.43 and total repayments are S$901,122.43. After five years, the balance is S$517,922.42. Displayed amounts are rounded to cents; internal calculations retain precision.
How prepayments work here
The regular payment stays at the original base payment plus your recurring extra amount. A one-off amount is added in its chosen month. Payments are capped at the amount then owed, so an oversized prepayment does not create a negative balance. The final payment may be smaller than the regular amount. The annual table includes the final partial year.
This models a shorter repayment period, not a lender recalculating a lower monthly instalment after prepayment. It also does not model an offset account, balloon, payment holiday or changing rates. For a rate reset, start another scenario with the outstanding balance and remaining term at that point.
Formula and reconciliation
For principal P, monthly rate r and n months, payment = P × r ÷ [1 − (1 + r)−n]. At zero interest, payment = P ÷ n. Each month: interest = opening balance × r; principal repaid = actual payment − interest; closing balance = opening balance − principal repaid. Total repayments equal original principal plus total interest.
Confirm actual repayment permission
Bank packages may have lock-ins, notice periods, minimum amounts or prepayment charges. HDB partial capital repayments have their own minimum amounts and application process. A hypothetical S$100 monthly extra here is not a statement that HDB accepts S$100 ad-hoc capital repayments. MoneySense: home loans, repricing and refinancing. HDB: partial capital repayment requirements.
Compare the result with interest cost and repayment restrictions before reallocating a cash reserve.
FAQ
Does the yearly schedule include an incomplete final year?
Yes. It includes every repayment and shows the number of months in each year, including the last partial year.
Does a lump sum lower my future monthly payment here?
No. The model keeps the base payment and shortens repayment. Lender recasting to a lower payment is a different scenario.
Are fees and changing rates included?
No. The calculation holds the rate constant and excludes fees and penalties.
Related guides and calculators
References
Sources checked 14 September 2026. Examples use stated assumptions and are not lender or CPF payout quotes.
Last updated: 14 Sep 2026 · Editorial Policy · Advertising Disclosure · Corrections