Bank Account Compound Interest Calculator

Compound interest is the interest calculated on the initial principal and also on the accumulated interest of previous periods. This calculator helps you determine how much your bank account will grow over time with compound interest.

How to Use This Calculator

To calculate your future bank balance with compound interest:

Enter the initial deposit amount in the "Principal" field
Input the annual interest rate (APR) in the "Annual Interest Rate" field
Select the compounding frequency (annually, semi-annually, quarterly, monthly, or daily)
Enter the number of years you plan to keep the money in the account
Click the "Calculate" button to see your results

The calculator will display your future value, total interest earned, and a growth chart showing your account balance over time.

The Compound Interest Formula

The future value (FV) of an investment with compound interest is calculated using this formula:

FV = P × (1 + r/n)^(n×t)

Where:

FV = Future Value
P = Principal amount (initial investment)
r = Annual interest rate (in decimal)
n = Number of times interest is compounded per year
t = Time the money is invested for, in years

For example, if you invest $1,000 at 5% annual interest rate compounded monthly for 10 years, the calculation would be:

FV = 1000 × (1 + 0.05/12)^(12×10)

Which equals approximately $1,647.01

The total interest earned would be the future value minus the principal amount.

Worked Example

Let's say you deposit $5,000 into a savings account with a 3.5% annual interest rate, compounded quarterly, for 7 years.

Using the formula:

FV = 5000 × (1 + 0.035/4)^(4×7)

Calculating step by step:

Divide the annual rate by the number of compounding periods: 0.035/4 = 0.00875
Add 1 to this value: 1 + 0.00875 = 1.00875
Calculate the exponent: 4 × 7 = 28
Raise the value to the power of 28: 1.00875^28 ≈ 1.2836
Multiply by the principal: 5000 × 1.2836 ≈ 6,418.00

So your account would grow to approximately $6,418.00 after 7 years, with $1,418.00 in total interest earned.

Frequently Asked Questions

How often should I compound my interest?

The more frequently your interest is compounded, the higher your future value will be. However, most banks compound interest daily, monthly, or annually. Daily compounding gives you the highest return.

Is compound interest taxable?

Compound interest earned on savings accounts is generally tax-free. However, if you withdraw the money, you may be subject to capital gains taxes depending on your country's tax laws.

What's the difference between APR and APY?

APR (Annual Percentage Rate) is the simple annual interest rate, while APY (Annual Percentage Yield) takes into account the effect of compounding. APY is always higher than APR for the same account.