Compute the future balance, principal contributed, and accumulated interest of a money market account with regular deposits.
Input Data
Results
At a glance:A money market account earns monthly-compounded interest; its future value combines the initial deposit, recurring deposits, and accumulated interest.
Formula
finalBalance = initialDeposit·(1+r)^n + monthlyDeposit·((1+r)^n - 1)/r
totalContributions = initialDeposit + monthlyDeposit·months
accumulatedInterest = finalBalance - totalContributions
$$FV = PV \left(1 + \tfrac{r}{12}\right)^{12t} + PMT \cdot \dfrac{\left(1 + \frac{r}{12}\right)^{12t} - 1}{\frac{r}{12}}$$$$Interest = FV - \left(PV + PMT \cdot 12t\right)$$How to Use
- Enter the initial deposit.
- Enter the monthly deposit (0 if none).
- Enter the annual rate and number of years.
- Review the future balance, total principal, and accumulated interest.
FAQ
What is the difference between a money market account and a regular savings account?
A money market account usually pays a higher rate but may require a higher minimum balance and limit the number of withdrawals per month. It places funds into short-term, low-risk money-market instruments, so its rate is generally above that of a demand savings account.
When is interest credited?
This calculator assumes monthly compounding with deposits made at month-end (an ordinary annuity). The actual crediting frequency follows your bank's terms, so check the account details.
Is a money market account risky?
It is generally considered low risk, but the rate floats with the market and there is no guarantee beyond deposit protection. Before investing, understand whether the rate is floating, and whether there are fees or minimum-balance requirements.
Money market account, time deposit or savings — where should my spare cash go?
All three are common low-risk places to park cash, but they trade off rate, flexibility and restrictions differently. A demand savings account is the most flexible (withdraw anytime) but usually pays the least — good for daily spending and emergency cash. A time deposit locks a sum for a fixed term in exchange for a higher, fixed rate — ideal for money you are sure not to need soon; you can ladder several deposits to keep some liquidity. A money market account sits in between: a higher rate than savings while retaining fair access, but often with a minimum-balance requirement and monthly withdrawal limits — suited to larger idle cash you want both earning and fairly liquid. Choose by how soon you need the money, and always check whether the rate is fixed or floating, plus any fees and limits.
Why does a few percentage points of rate make such a big difference in long-run interest? How do compounding and deposit frequency matter?
A gap of a few points is modest in isolation, but under compounding and ongoing contributions it accumulates noticeably, especially with a large principal and long term. Interest is roughly proportional to the rate, so at 0.5% vs 4% on a HK$200k base over two years, even before compounding the gap is already large, and monthly compounding then amplifies it — interest rolls into principal each month and earns again. Higher rate, longer term and more frequent compounding all widen the gap beyond a simple linear guess. The timing of deposits also matters: this tool assumes deposits at month-end; depositing at month-start would give slightly more because each contribution compounds one month longer. Practical takeaways: use high-rate tools during rising-rate periods; compare rates carefully when the principal or term is large; remember MMA and savings rates are mostly floating; and watch minimum-balance and withdrawal rules that could erode the real return.
References
Content review: Calculatorism Finance Team. Results are for reference only; please refer to the relevant authorities for the official figures.