Project a money market deposit account using its advertised annual percentage yield. Add recurring savings and optional maintenance fees to see the interest earned, costs paid, and balance remaining at the end of the term.
How to estimate account growth
Enter the opening deposit and an APY from the account terms or a clearly chosen scenario. The example rate is illustrative. Choose whole years and additional months, then add monthly, quarterly, or yearly deposits if needed. Beginning-of-period deposits earn interest sooner than end-of-period deposits.
The account fee section accepts a monthly maintenance charge and an optional opening-balance threshold for waiving it. Leave the threshold blank if there is no waiver. Entering zero waives every monthly fee in this model. The fee test is made before the month's deposit, so a deposit that reaches the threshold can qualify the account starting with the next month.
Formula
monthly rate = (1 + APY / 100)^(1/12) − 1
interest = interest-bearing balance × monthly rate
closing balance = opening balance + deposits + interest − fees paid
net earnings = total interest − total fees paid
APY already includes compounding. The monthly rate is the rate that reproduces that APY over twelve equal periods. Without cash flows or fees, a 4% APY turns 10,000 into 10,400 after one year. Applying 4% divided by twelve each month would instead treat 4% as a nominal rate and give a different result.
Examples
One year without account fees
An initial deposit of 10,000 at 4% APY, with no extra deposits or fees, earns 400 over one year. The projected balance is 10,400.
Deposits and fees at zero interest
Start with 1,000, add 100 at each month-end, and pay a 5 monthly fee for twelve months at 0% APY. Deposits total 1,200, fees total 60, and the ending balance is 2,140.
Crossing a fee-waiver threshold
With a 900 opening balance, 100 monthly deposits, a 5 fee, and a 1,000 opening-balance waiver, the first month closes at 995 when APY is zero. Month two still starts below the threshold, so another fee applies. Month three starts at 1,090 and qualifies for the waiver.
Reading the monthly schedule
Each row shows the opening balance, contribution, interest, paid fee, unfunded fee, and closing balance. Interest is computed before the month-end fee. Beginning deposits are included in that month's interest; ending deposits are not. Quarterly and yearly deposits occur at the start or end of their respective periods, with no extra ending deposit for an incomplete period.
The chart follows the same closing balances as the table. Gross interest and net earnings answer different questions: an account can earn interest while losing money overall after fees. Compare fee costs as well as the stated APY.
What this projection assumes
The APY stays constant, there are no withdrawals, and every month represents one twelfth of a year. Actual interest postings can differ because of daily balances, calendar lengths, rate changes, rounding, deposit availability, tiered rates, and account-specific terms. Taxes and promotional bonuses are excluded. The model does not reproduce a bank statement or determine whether an account meets insurance requirements.
A money market deposit account is different from a money market mutual fund. This calculator models a deposit balance at an assumed APY, without fund share prices or investment distributions. The CFPB explains money market accounts and maintenance-fee requirements. For the annual-yield framework, see its APY calculation reference.