Interest Calculator for Money Market Account
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Reviewed by Calculator Editorial Team
Money market accounts offer high interest rates but come with different interest calculation methods. This calculator helps you determine how much interest you'll earn based on your deposit amount, interest rate, and compounding frequency.
How to Use This Calculator
To calculate your money market account interest:
- Enter your initial deposit amount in dollars
- Input the annual interest rate (APR) as a percentage
- Select how often your interest is compounded (daily, monthly, quarterly, annually)
- Enter the number of years your money will stay in the account
- Click "Calculate" to see your results
The calculator will show you both the total interest earned and the future value of your account, including a chart showing your growth over time.
Formula Used
The interest calculation uses the compound interest formula:
Compound Interest Formula
A = P(1 + r/n)^(nt)
Where:
- A = the future value of the investment/loan, including interest
- P = the principal investment amount (the initial deposit or loan amount)
- r = the annual interest rate (decimal)
- n = the number of times that interest is compounded per year
- t = the time the money is invested or borrowed for, in years
Interest earned = A - P
Note
This calculator assumes the interest rate is compounded according to the selected frequency. Some money market accounts may offer simple interest or tiered rates, which would require different calculations.
Worked Example
Let's calculate the interest earned on $10,000 deposited at 2.5% annual interest rate compounded monthly for 3 years.
| Principal (P) | $10,000 |
|---|---|
| Annual Interest Rate (r) | 2.5% or 0.025 |
| Compounding Frequency (n) | Monthly (12 times per year) |
| Time (t) | 3 years |
Using the formula:
A = 10000(1 + 0.025/12)^(12×3) = $10,838.42
Interest earned = $10,838.42 - $10,000 = $838.42
This example shows how compound interest can grow your money over time in a money market account.
Frequently Asked Questions
What's the difference between APR and APY?
APR (Annual Percentage Rate) is the simple annual interest rate, while APY (Annual Percentage Yield) shows the actual interest rate after compounding. APY is always higher than APR for compounded accounts.
How often should I compound my money market interest?
More frequent compounding (daily, monthly) generally yields higher returns. However, check your account terms as some institutions may limit compounding frequency.
Can I withdraw money from a money market account without penalty?
Withdrawal rules vary by institution. Some accounts allow unlimited withdrawals, while others may have minimum balance requirements or restrictions on the number of withdrawals per month.