Money Market Account Calculator
Project a money market account balance from the starting amount, APY, years and optional monthly deposits. Includes a worked 3-year example.
Results · USD
Future value
- Interest earned
- $1,411.66
- Total deposits
- $10,000.00
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Educational estimates · not financial advice · free, no signup
How this was calculated
Monthly rate derived from APY: r_m = (1 + APY)^(1/12) − 1. Balance compounds monthly; deposits added end of month.
Want more detail? Full formula notes & FAQs ↓
Detailed guide
What it is, how to use it, how to read the numbers, common mistakes, a worked example, formulas, and FAQs.
What this calculator is
A money market account is a savings-style deposit account that pays variable interest and may offer limited check-writing. Banks quote its yield as an annual percentage yield, APY, which already reflects compounding. This calculator turns an APY, a starting balance, a term in years and optional monthly deposits into a projected balance. Rates on money market accounts change, so the result is a projection at a constant APY, not a promise. Fees, minimum balances and tax on interest are not included. It is useful for comparing offers and for seeing how much of your balance growth comes from deposits versus interest.
When to use / who it helps
- You are comparing money market accounts with different APYs.
- You want to see what a balance could grow to over a few years.
- You are planning to add a fixed amount each month.
- You want to see interest earned separately from deposits.
- You are comparing a money market account with a CD or savings account.
How to use
Steps
- Enter the starting balance.
- Enter the APY quoted by the bank.
- Enter the number of years.
- Add a monthly deposit if you plan regular contributions.
- Read the future value, interest earned and total deposits.
- Re-run with a lower APY to see sensitivity to rate cuts.
How to interpret results
- Future value is the projected balance if the APY stays constant.
- Interest earned equals the future value minus starting balance and deposits.
- APY already includes compounding, so do not compound it again.
- Variable rates may move up or down during the term.
- Taxes on interest and any fees reduce what you keep.
Common mistakes & gotchas
- Entering the nominal rate (APR) in the APY field.
- Assuming the advertised APY is guaranteed for the entire term.
- Ignoring minimum-balance or monthly fees.
- Forgetting that interest is usually taxable.
- Comparing accounts without checking insurance coverage limits.
Worked example
Worked example — $10,000 at 4.5% APY for 3 years, no deposits
- With APY, the yearly growth factor is 1.045.
- After 3 years: 10,000 × 1.045³ = 10,000 × 1.14117 = $11,411.66.
- Interest earned: 11,411.66 − 10,000 = $1,411.66.
- Adding a $100 monthly deposit would raise the balance further, because each deposit also earns interest for the remaining months.
Result: $11,411.66 after three years, of which $1,411.66 is interest.
To load the form's own demo values, tap Try example above the Calculate button.
How to calculate / formula
Monthly rate derived from APY: r_m = (1 + APY)^(1/12) − 1. Balance compounds monthly; deposits added end of month.
Frequently asked questions
What is the difference between APY and APR?
APY includes the effect of compounding within the year; APR does not. APY is the better figure for comparing deposits.
Is the rate on a money market account fixed?
Usually not. Banks can change it, so projections are estimates.
Are money market accounts insured?
Accounts at banks may be covered by deposit insurance up to a limit in many countries; check your institution and local rules.
How is this different from a money market fund?
A fund is an investment product and is not a deposit account. This tool models a deposit account.
Does this include taxes?
No. Interest is generally taxable in many countries.
How often is interest paid?
Often monthly, but the APY already reflects compounding.