Money Market Calculator
Enter an opening deposit, optional monthly deposits and the APY to see what your money market account will be worth and how much interest it earns.
Free, no sign-upRuns in your browserHow we calculate
Added at the end of each month. Use 0 for none.
Banks advertise APY. Pick the interest rate only if you have the nominal rate.
Optional. Interest is ordinary income; use your marginal rate.
- Total interest
- $3,711.28
- APY used
- 4%
- Total deposited
- $25,000.00
- Interest in month 1
- $32.74
| Year | Deposits | Interest | Balance |
|---|---|---|---|
| 1 | $3,000.00 | $454.61 | $13,454.61 |
| 2 | $3,000.00 | $592.79 | $17,047.41 |
| 3 | $3,000.00 | $736.51 | $20,783.91 |
| 4 | $3,000.00 | $885.97 | $24,669.88 |
| 5 | $3,000.00 | $1,041.41 | $28,711.28 |
How this was calculated
- Monthly rate equivalent to the APY: (1 + 0.040000)^(1/12) − 1 = 0.32737%.
- Each month the balance earns that rate, then the $250.00 deposit is added; repeated for 60 months.
- Final balance $28,711.28 = $25,000.00 deposited + $3,711.28 interest.
Assumes a constant rate. Money market rates are variable and can change at any time. Not financial advice.
How this money market calculator works
A money market account pays a variable rate that banks quote as an APY (annual percentage yield). Under the Truth in Savings Act (Regulation DD) the APY already includes compounding, so one year of growth is simply balance × (1 + APY). This money market calculator turns the APY into the equivalent monthly rate, (1 + APY)1/12 − 1, then adds interest and your monthly deposit month by month for the years you choose.
If you only know the nominal interest rate, switch the rate type and pick the compounding. The calculator first converts it to APY with (1 + r/n)n − 1. A 3.9% rate compounded daily is a 3.977% APY.
Worked example
Put $10,000 in a money market account at 4.00% APY with no further deposits. After one year you have $10,000 × 1.04 = $10,400. After five years it is $10,000 × 1.045 = $12,166.53. Add $250 a month and the five-year balance rises to about $28,711, of which $25,000 is your own money.
Money market account vs. savings account vs. CD
- Savings account: variable rate, no check writing. Often the lowest rate.
- Money market account: variable rate, often a higher tier for larger balances and limited checks or a debit card. Banks may require a minimum balance.
- CD: a fixed rate for a fixed term, with a penalty for early withdrawal. Use the CD calculator for that.
Not the same as a money market fund. A money market account is a bank deposit, insured by the FDIC (or NCUA at credit unions) up to $250,000 per depositor, per bank, per ownership category. A money market fund is a brokerage investment and is not FDIC-insured.
When the result is misleading
The rate is not locked. If the bank cuts its rate next month, your real balance will be lower than shown, so run the calculator with a lower rate as a check. Fees and minimum-balance rules can also eat into the interest, and the interest is taxable income in the year it is paid. Enter your marginal tax rate to see the after-tax interest. Sources: Regulation DD (12 CFR 1030), FDIC deposit insurance rules.
Frequently asked questions
How is money market interest calculated?
The APY already includes compounding, so one year of growth is balance × (1 + APY). $10,000 at 4% APY becomes $10,400 after one year and $12,166.53 after five years.
What is the difference between APY and the interest rate?
The interest rate is the nominal yearly rate; APY includes compounding. A 3.9% rate compounded daily is a 3.977% APY. Compare accounts on APY.
How do monthly deposits change the balance?
Each deposit starts earning interest the month after it is made. $10,000 at 4% APY with $250 added every month grows to about $28,711 in five years, of which $25,000 is your own money.
Is a money market account the same as a money market fund?
No. A money market account is a bank deposit insured by the FDIC (or NCUA) up to $250,000 per depositor, per bank, per ownership category. A money market fund is a brokerage investment and is not insured.
Is money market interest taxable?
Yes. Interest is ordinary income in the year it is paid, taxed at your marginal rate. Enter your tax rate in the calculator to see the interest after tax.