Savings Calculator
Estimate the final balance, principal and interest of savings under compounding and regular contributions.
Input Data
Results
Savings growth: principal vs interest earned
At a glance:The Savings Calculator (savings calculator) uses the compound-interest formula to project the final balance of savings with regular contributions. It combines an initial principal, periodic contribution, annual rate and compounding frequency: final balance = principal × (1 + r/n)^(n×t) + contribution × [((1 + r/n)^(n×t) − 1) ÷ (r/n)], where r is the annual rate, n is compounding per year and t is years; interest earned = final balance − total principal contributed. Consistent contributions plus compounding significantly amplify savings over time, suitable for regular savings plans, time deposits and education funds.
Formula
Final balance = principal × (1 + r/n)^(n×t) + contribution × [((1 + r/n)^(n×t) − 1) ÷ (r/n)].
Total principal contributed = principal + contribution × (n × t).
Interest earned = final balance − total principal contributed.
$$FV = P\left(1 + \dfrac{r}{n}\right)^{nt} + PMT \times \dfrac{\left(1 + \frac{r}{n}\right)^{nt} - 1}{\frac{r}{n}}$$$$\text{Interest} = FV - \left(P + PMT \times n t\right)$$How to Use
- Enter the initial principal and periodic contribution.
- Set the annual rate, term and compounding per year.
- Instantly get the final balance, principal and interest earned.
FAQ
Must the contribution frequency match the compounding frequency?
This calculator assumes they are the same (e.g. 12 compounds per year means a monthly contribution). If your actual contribution frequency differs, set 'compounding per year' to match your contribution frequency for the closest estimate.
Does a higher compounding frequency always mean more return?
At the same nominal annual rate, more frequent compounding gives a slightly higher effective return (APY) and a slightly larger final balance, but the marginal gain shrinks quickly. What really moves the result is the rate, the contribution amount and the time horizon.
Is the contribution made at the start or end of the period?
This calculator uses the end-of-period (ordinary) annuity assumption — contributions are deposited at each period end. With start-of-period contributions the final balance would be slightly higher because each payment compounds one extra period.
Is savings deposited in Hong Kong protected?
Yes. The Deposit Protection Scheme, run by the Deposit Protection Board, covers up to HK$800,000 per depositor per member bank (raised from HK$500,000 on 1 October 2024), including savings, current and time deposits up to 5 years, with no registration or fee. If you exceed the cap, spread deposits across different member banks.
What rate should I use for the estimate?
Use a conservative, reasonable assumption by asset type. HKD savings rates are generally low; time deposits run a few percent depending on market; equities or funds have higher long-term expected returns but more volatility. Run optimistic, neutral and conservative rates to see the range.
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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.