Bank Account Interest Calculator

Calculate how much interest you'll earn on your bank account with our free online calculator. Learn how to compute interest earned, compare rates, and understand the difference between APR and APY.

How to Use This Calculator

Using our bank account interest calculator is simple:

Enter the principal amount (the initial deposit or balance)
Select the interest rate (APR or APY)
Choose the compounding frequency (annually, monthly, daily, etc.)
Enter the time period in years
Click "Calculate" to see your results

The calculator will display the total interest earned and the final amount in your account after the specified time period.

Interest Calculation Formula

The formula for compound interest is:

A = P (1 + r/n)^(nt) where: A = the future value of the investment/loan, including interest P = the principal investment 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

For simple interest, the formula is:

A = P (1 + rt) where: A = the amount of money accumulated after n years, including interest. P = the principal amount (the initial amount of money) r = the annual interest rate (decimal) t = the time the money is invested or borrowed for, in years

Most bank accounts use compound interest, which means interest is calculated on both the initial principal and the accumulated interest from previous periods.

APR vs APY: What's the Difference?

APR (Annual Percentage Rate) is the simple interest rate your bank advertises. APY (Annual Percentage Yield) is the actual interest rate you earn after compounding is taken into account.

Term	Definition
APR	The simple interest rate your bank advertises
APY	The actual interest rate you earn after compounding
Compound Interest	Interest calculated on the initial principal and also on the accumulated interest of previous periods
Simple Interest	Interest calculated only on the original principal

For example, if a bank offers a 1% APR compounded monthly, the actual APY would be higher than 1% because of compounding.

Worked Examples

Example 1: Simple Interest Calculation

If you deposit $1,000 at a simple interest rate of 5% for 3 years:

A = P (1 + rt) A = $1,000 (1 + 0.05 * 3) A = $1,000 (1 + 0.15) A = $1,150 Interest earned = $150

Example 2: Compound Interest Calculation

If you deposit $1,000 at an annual interest rate of 5% compounded monthly for 3 years:

A = P (1 + r/n)^(nt) A = $1,000 (1 + 0.05/12)^(12*3) A = $1,000 (1 + 0.004167)^36 A ≈ $1,161.62 Interest earned ≈ $161.62

Frequently Asked Questions

How is bank interest calculated?

Bank interest is typically calculated using compound interest formulas, where interest is calculated on both the initial principal and the accumulated interest from previous periods.

What is the difference between APR and APY?

APR is the simple interest rate your bank advertises, while APY is the actual interest rate you earn after compounding is taken into account. APY is always higher than APR for compounding accounts.

How often should interest be compounded?

Interest is typically compounded daily, monthly, quarterly, or annually. More frequent compounding periods result in higher earnings over time.

Is there a penalty for early withdrawal?

Early withdrawal penalties vary by bank and account type. Some accounts may charge fees or reduce interest rates for early withdrawals.

How can I maximize my bank interest earnings?

To maximize earnings, choose accounts with higher interest rates, compound interest, and frequent compounding periods. Also consider opening multiple accounts or using online banks that often offer higher rates.