Money Market Account Calculator - APY Cash Growth

A money market account calculator estimates how a deposit account may grow when you enter the account APY, starting balance, monthly deposits, withdrawals, fees, and tax assumption. Use it before moving cash from checking, comparing a bank money market offer with a savings account, deciding whether a minimum balance is worth meeting, or checking whether a large cash reserve may sit above an insurance threshold.

• • Compare account offers: Enter the same balance and months with different APYs to see the dollar difference after fees and planned cash flows.
• • Plan a cash reserve: Project an emergency fund or business reserve while keeping withdrawals and monthly service charges visible.
• • Review a large balance: Use the insurance limit field to flag projected dollars above the threshold you want to monitor.
• • Estimate taxes on interest: Apply one planning tax rate to gross interest so after-tax interest is not hidden by the headline APY.

Money market accounts are usually chosen for cash that should stay available while still earning interest. The result should be read as a planning estimate, not a bank disclosure, because the bank's agreement controls actual rate changes, balance tiers, transaction rules, fees, and interest-crediting dates.

The calculator works from APY because APY is the number consumers normally see when comparing deposit accounts. If you only know interest earned over a period, annualize that amount first, then return here to model monthly deposits, withdrawals, fees, and the ending balance.

When an account statement gives interest earned instead of a quoted APY, APY Calculator can annualize that yield before you model monthly cash flows here.

The projection converts APY into an effective monthly rate, applies interest each month, then adds deposits and subtracts withdrawals and fees.

• Opening balance: The starting account balance before the first projected month.
• APY: The annual percentage yield quoted by the institution, entered as a percent.
• Monthly deposit: A recurring end-of-month addition to the account.
• Monthly withdrawal and fee: Recurring end-of-month reductions that lower the balance available for later interest.
• Tax rate: A planning rate applied only to gross interest, not to deposits or principal.

The calculator compounds monthly because the cash-flow inputs are monthly. It does not assume the bank credits interest monthly in every case; it converts the annual APY into a monthly equivalent so deposits, withdrawals, and fees can be modeled on one schedule.

Monthly deposits are added after that month's interest calculation. This means a deposit made at the end of the month starts earning in the next cycle. If your real deposit arrives at the beginning of each month, the estimate will be slightly conservative.

According to Consumer Financial Protection Bureau Appendix A to Regulation DD, annual percentage yield measures total interest paid on an account based on the interest rate and compounding frequency.

For a general savings projection that is not tied to a money market account offer, Savings Calculator gives a broader view of deposits and future balance.

These terms explain why the percentage shown in an offer can differ from the cash interest you actually care about.

APY is useful because it already folds compounding into one annual number. It still does not describe every account rule. Fees, balance tiers, promotional periods, and rate changes can easily matter more than a small APY difference.

Do not treat money market deposit accounts and money market mutual funds as interchangeable. A bank money market deposit account is a deposit product, while a money market fund is an investment product with different risks and protections.

After you know the account's likely yield, Savings Goal Calculator can translate that yield into a monthly funding plan for a target balance.

Use the fields in the same order you would review a bank offer: balance, APY, time, cash flows, costs, and coverage threshold.

1. 1 Enter the starting balance: Use the balance that will be in the account at the beginning of the projection.
2. 2 Enter the quoted APY: Use the APY from the rate sheet, account disclosure, or online banking page rather than a promotional headline without details.
3. 3 Set the projection length: Use the number of months you expect the cash to remain in the account before a major decision or withdrawal.
4. 4 Add recurring cash flows: Enter normal monthly deposits, withdrawals, and maintenance fees so the ending balance reflects real account use.
5. 5 Review tax and coverage rows: Use the tax estimate and above-limit row as planning prompts, then check your institution and account ownership details.

Suppose you are parking $50,000 for two years, withdrawing $500 per month for planned expenses, and paying a $10 monthly service fee. At 3.75% APY, the calculator shows whether interest meaningfully offsets those outflows and how much cash remains at the end.

If the account you are comparing locks cash for a fixed term, CD Calculator is a closer match because it includes CD maturity and penalty assumptions.

The value of the calculator is not only the ending balance. It separates the drivers that usually get mixed together in account comparisons.

• • Separates deposits from interest: The net growth row may look strong because you added new money, while the interest row shows the account's actual earnings.
• • Makes fees visible: A monthly fee can erase part of a yield advantage, especially on smaller balances or short holding periods.
• • Supports cash-flow planning: Recurring withdrawals show whether the account can support planned spending while still earning interest.
• • Adds tax context: Interest is separated before and after the entered tax rate so the headline APY does not overstate spendable earnings.
• • Flags a coverage review: The above-limit row gives a simple prompt to review deposit insurance structure before holding a large balance.

This estimate is especially useful when two accounts have similar APYs but different balance requirements or fees. A higher APY may lose its advantage when the account requires a large minimum balance or charges a monthly fee you cannot avoid.

For longer projections with investment return assumptions, use a broader compound-interest model. A money market account projection is intentionally cash-focused and should not be stretched into stock, bond, or retirement planning. Run the money market account calculator again when a bank changes APY, fee terms, or balance tiers.

For long-range scenarios that mix deposits with investment-style return assumptions, Compound Interest Calculator supports a broader compounding model.

Several real account terms can move the result away from a simple APY projection, so review these factors before acting on the estimate.

• • The calculator uses one APY for the full projection and does not model promotional periods, tiered rate schedules, or midstream rate changes.
• • The tax estimate applies one user-entered rate to interest only; it does not handle federal, state, local, business, or account-specific tax rules.
• • The insurance row is a comparison prompt, not a coverage determination. Joint accounts, trust accounts, retirement accounts, and multiple banks can change actual coverage.

If the projected balance is near a rate tier, run a second scenario with the next APY. If the ending balance sits above the coverage threshold you entered, review the account title, bank, and ownership category instead of assuming the excess is uninsured.

For a fixed-term account with early withdrawal penalties, a CD model may be a closer fit than this account calculator. Money market accounts are usually more flexible, but the exact account agreement still controls fees and transaction limits.

Use a fresh scenario whenever an offer changes. A small APY increase can matter on a six-figure reserve, while a fee waiver can matter more on a smaller balance. Keeping those assumptions separate makes the result easier to explain to a household, finance team, or advisor.

According to Federal Deposit Insurance Corporation, FDIC deposit insurance covers $250,000 per depositor, per FDIC-insured bank, for each account ownership category.