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Finance Calc Kit
Savings

Money Market Account Calculator

Calculate future savings balance, total interest earned, and compound growth for money market accounts with recurring deposits.

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years

Estimated future balance

$23,108.32

After 5 years with monthly (12/yr) compounding

Total principal

$20,000.00

Initial deposit plus monthly contributions

Total interest

$3,108.32

Compound interest earned

Effective APY

4.594%

Nominal rate adjusted for compounding

Principal vs interest

Future balance$23,108.32
  • Principal deposited$20,000.0086.5%
  • Interest earned$3,108.3213.5%

How this money market balance is calculated

Month-by-month simulation with recurring deposits and compound interest.

  1. Convert the nominal rate to effective APY

    APY=(1+rn)n−1\mathrm{APY} = \left(1 + \frac{r}{n}\right)^{n} - 1

    Nominal rate r = 4.5%, compounding n = 12 times per year. Effective APY = 4.594%.

  2. Derive the equivalent monthly compounding rate

    rmonth=(1+rn)n/12−1r_{\text{month}} = \left(1 + \frac{r}{n}\right)^{n/12} - 1

    Each month, interest accrues at 0.3750% on the current balance.

  3. Simulate each month with deposits

    Starting balance $5,000.00. For 60 months: add $250.00 deposit, then apply monthly compounding. Final balance = $23,108.32.

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What is a money market account?

A money market account (MMA) is a deposit account offered by banks and credit unions that typically pays a higher annual percentage yield (APY) than a standard savings account while keeping funds relatively liquid. Many MMAs allow limited check writing and debit card access, making them useful for emergency reserves or short-term cash parking. Deposits at FDIC-insured banks or NCUA-insured credit unions are protected up to $250,000 per depositor, per insured institution, per ownership category.

This calculator projects your future balance by combining an initial deposit, recurring monthly contributions, and compound interest at your chosen compounding frequency. All math runs in your browser. To compare a lump-sum deposit without recurring contributions, use the compound interest calculator. For fixed-term bank deposits with payout options, try the FD calculator. To convert a stated nominal rate into an effective annual yield, use the APY calculator.

Money market account growth formulas

Banks often advertise a nominal annual interest rate along with a compounding schedule. The effective APY reflects how often interest is credited to your balance:

APY=(1+rn)n−1\mathrm{APY} = \left(1 + \frac{r}{n}\right)^{n} - 1

Where rr is the nominal annual rate (as a decimal) and nn is the number of compounding periods per year (365 for daily, 12 for monthly, 4 for quarterly, or 1 for annual).

When you add a fixed monthly deposit, the balance grows through a month-by-month simulation. Each month, your contribution is added first, then interest compounds at an equivalent monthly rate derived from the nominal annual rate:

rmonth=(1+rn)n/12−1r_{\text{month}} = \left(1 + \frac{r}{n}\right)^{n/12} - 1

For each month in the investment horizon, the simulator adds your monthly deposit to the balance, then applies rmonthr_{\text{month}} to the updated balance. Total interest equals the final balance minus all principal deposited (initial plus contributions).

Worked example

Suppose you open a money market account with a $5,000 initial deposit, contribute $250 per month, earn a 4.5% nominal annual rate compounded monthly, and hold the account for 5 years.

  • Compounding periods: n=12n = 12 (monthly)
  • Effective APY: (1+0.04512)12−1≈4.594%\left(1 + \frac{0.045}{12}\right)^{12} - 1 \approx 4.594\%
  • Monthly rate: (1+0.04512)1−1=0.375%\left(1 + \frac{0.045}{12}\right)^{1} - 1 = 0.375\%
  • Total principal deposited: $5,000 + ($250 × 60 months) = $20,000
  • Estimated future balance after 5 years: approximately $23,108
  • Total compound interest earned: approximately $3,108

Daily compounding would produce a slightly higher balance because interest is credited more frequently. The difference is modest at typical MMA rates but grows with larger balances and longer time horizons.

Money market account vs other savings products

Money market accounts sit between standard savings accounts and certificates of deposit (CDs). Savings accounts offer maximum flexibility but often pay lower yields. CDs lock your money for a fixed term in exchange for a guaranteed rate. MMAs balance higher yields with limited transaction access. Compare fixed-term yields with the CD calculator or model daily compounding on a high-yield savings balance with the compound daily interest calculator.

How compounding frequency affects earnings

More frequent compounding means interest earns interest sooner within each year. At a 4.5% nominal rate, monthly compounding produces an APY of about 4.594%, while daily compounding pushes the effective yield slightly higher to about 4.602%. The gap widens as rates rise or balances grow, which is why comparing APY rather than the nominal rate is essential when shopping for accounts.

Frequently asked questions

What is the difference between a money market account and a high-yield savings account?
Both are FDIC- or NCUA-insured deposit accounts that pay compound interest. Money market accounts often include check-writing and debit card access, while high-yield savings accounts typically limit withdrawals to electronic transfers. Rates, minimum balances, and fee structures vary by institution, so compare the effective APY rather than the advertised nominal rate.
How does compounding frequency affect money market earnings?
More frequent compounding (daily versus monthly or quarterly) generates slightly higher total interest because each interest credit begins earning its own interest sooner. The calculator converts your nominal rate and compounding schedule into an effective APY so you can compare accounts on equal terms.
Are money market account returns guaranteed?
Principal in an FDIC-insured bank or NCUA-insured credit union is protected up to statutory limits, but the interest rate itself is variable and can change when market conditions shift. This calculator assumes a constant rate over the full period, which is useful for planning but may differ from actual future yields.
Should I use APY or the nominal rate when comparing MMAs?
Always compare effective APY when evaluating deposit products. APY accounts for compounding frequency, so two accounts with the same nominal rate but different compounding schedules will have different true yields. Use the APY calculator to convert any stated rate.
Can I model only a lump sum without monthly deposits?
Yes. Set the monthly deposit to $0 and enter your starting balance as the initial deposit. For more advanced contribution schedules and inflation adjustments, use the investment calculator or compound interest calculator.

Resources and references

The formulas and methods in this calculator were checked against these independent sources.