Loan Repayment Calculator
From loan amount, annual rate and term, compute the amortising monthly payment, total repayment and total interest.
Input Data
Results
At a glance:The Loan Repayment calculator estimates the monthly payment, total repayment and total interest of an amortising loan. Amortising (annuity) keeps the monthly payment fixed, with the interest share falling and principal share rising each month until the balance is cleared at maturity. Compare term/rate combinations to balance total cost and cash flow.
Formula
Monthly rate r = annual ÷ 12; total months n = years × 12.
Monthly = loan × r × (1+r)^n ÷ ((1+r)^n − 1).
Total repayment = monthly × n; total interest = total repayment − loan.
$$r = \dfrac{\text{annual}\%}{12},\quad n = \text{years} \times 12$$$$\text{Monthly} = P \times \dfrac{r(1+r)^n}{(1+r)^n - 1}$$$$\text{Total Interest} = \text{Monthly} \times n - P$$How to Use
- Enter the loan amount.
- Enter the annual rate and term.
- View the monthly payment, total repayment and total interest.
Loan HK$10,000 at 7% — monthly payment and total interest by term
| Term | Monthly | Total repayment | Total interest |
|---|---|---|---|
| 3 yr | 308.77 | 11,115.75 | 1,115.75 |
| 5 yr | 198.01 | 11,880.72 | 1,880.72 |
| 7 yr | 150.93 | 12,677.85 | 2,677.85 |
| 10 yr | 116.11 | 13,933.02 | 3,933.02 |
Case Studies
Case 1: Interest vs principal split in a payment
Mr Chow borrows 300,000 at 7% over 5 years (60 months) and wants the payment structure.
Monthly ≈ 5,940.36. First-month interest = 300,000 × 7% ÷ 12 = 1,750; principal repaid only ≈ 4,190; as principal falls, interest drops and principal repaid rises. Total interest ≈ 56,422.
Same 5,940 payment: early on nearly 30% is interest, later almost all principal — explaining 'years in, balance still high' and why early prepayment saves the most interest.
Case 2: Term 5 vs 8 years — interest gap
Ms Chan borrows 300,000 at 7%, comparing 5 vs 8 years.
5 yr: monthly ≈ 5,940, total interest ≈ 56,422. 8 yr: monthly ≈ 4,090, total interest ≈ 92,651.
Extending 3 years lowers the monthly by ~1,850 but raises total interest by ~36,000. If affordable, a shorter term is cheaper long run.
FAQ
Why does a longer term cost more interest?
A longer term slows principal repayment, so the unpaid balance accrues interest longer — total interest rises. The monthly is easier but the overall cost is higher.
Does the interest/principal split change?
Yes. Under amortising, the payment is fixed but early interest is high and principal low; as the balance falls, interest drops and principal repaid rises.
Why does the result differ from the bank?
This tool assumes a fixed rate, on-time payments, no fees, insurance or prepayment penalties. The lender's APR and fee structure may differ — use the formal quote and contract for the exact figure.
What share of income is safe for the monthly payment; how do HK banks approve?
A sound rule: keep the total monthly payment of all debts (this loan, mortgage, cards, instalments) within a reasonable share of income, with a buffer for rate rises and surprises. In HK, banks cap the Debt Servicing Ratio (DSR) and run an interest-rate stress test — assuming rates rise, whether your payment-to-income stays acceptable; fail and you get less. Even private loans are assessed on income, existing debt and credit record. From your side: (1) run this at the current and a higher rate to confirm affordability under hikes; (2) avoid stacking multiple high-interest loans; (3) keep a 3–6 month emergency fund; (4) borrow only for necessity or to improve finances. DSR caps and stress tests follow the latest HKMA guidance; this tool is for estimation, not advice.
Why does the result differ from the lender's quote?
This tool uses the standard fixed-rate, amortising, monthly-compounding, on-time model — good for planning, but may differ for several reasons: (1) fees excluded — arrangement/handling fees, insurance, late/prepayment penalties add to the true total cost beyond this interest; (2) rate definition — a 'flat rate' quote is far costlier than the APR reflecting the falling balance, not directly comparable; (3) floating rate — future rate moves change the payment; (4) rounding and accrual-day differences; (5) results rounded to 2 decimals. Use it to compare term/rate scenarios and estimate magnitude; for exact payment, fees and APR, use the formal quote and contract, comparing on the fee-inclusive APR.
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References
Content review: Calculatorism Finance Team. Results are for reference only; please refer to the relevant authorities for the official figures.