Calculate Savings Account Interest
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Reviewed by Calculator Editorial Team
Savings account interest is the earnings generated from money deposited in a financial institution. Calculating savings account interest helps you understand how much your money will grow over time, allowing you to make informed financial decisions. This guide explains how to calculate savings account interest, the difference between APR and APY, and how compound interest works.
How to Calculate Savings Account Interest
Calculating savings account interest involves determining the earnings from your deposited funds based on the interest rate and time period. The basic formula for simple interest is:
Where:
- Principal is the initial amount of money deposited
- Rate is the annual interest rate (expressed as a decimal)
- Time is the number of years the money is invested
For example, if you deposit $1,000 at a 2% annual interest rate for 5 years, your simple interest would be:
However, most savings accounts use compound interest, which means interest is calculated on both the initial principal and the accumulated interest from previous periods. The compound interest formula is:
Where:
- A is the amount of money accumulated after n years, including interest
- P is the principal amount (the initial amount of money)
- r is the annual interest rate (decimal)
- n is the number of times interest is compounded per year
- t is the time the money is invested for, in years
For example, if you deposit $1,000 at a 2% annual interest rate compounded monthly for 5 years, your final amount would be:
This means you would earn approximately $104.08 in interest over the 5-year period.
APR vs APY: What's the Difference?
When comparing savings accounts, you'll often see two different interest rates: APR (Annual Percentage Rate) and APY (Annual Percentage Yield).
APR is the simple interest rate that the bank advertises. It doesn't account for compounding.
APY is the effective annual interest rate, which takes into account compounding and other factors. It's a more accurate representation of how much you'll earn.
For example, if a savings account offers a 2% APR compounded monthly, the APY would be approximately 2.02%. The difference becomes more significant with higher interest rates or more frequent compounding periods.
To calculate APY from APR, you can use the following formula:
Where n is the number of compounding periods per year.
Understanding Compound Interest
Compound interest is the process where interest is calculated on the initial principal and also on the accumulated interest of previous periods. This means your money grows exponentially over time rather than linearly.
The more frequently interest is compounded, the more your money will grow. Common compounding periods include:
- Annually (once per year)
- Semi-annually (twice per year)
- Quarterly (four times per year)
- Monthly (twelve times per year)
- Daily (365 times per year)
The table below shows how compound interest works with different compounding frequencies:
| Compounding Frequency | APY (2% APR) | APY (5% APR) |
|---|---|---|
| Annually | 2.00% | 5.00% |
| Semi-annually | 2.01% | 5.05% |
| Quarterly | 2.02% | 5.12% |
| Monthly | 2.02% | 5.13% |
| Daily | 2.02% | 5.13% |
As you can see, the difference between APR and APY becomes more pronounced with higher interest rates and more frequent compounding.
Example Calculation
Let's walk through a complete example to illustrate how to calculate savings account interest.
Example Scenario
You deposit $5,000 in a savings account that offers a 3% APR compounded monthly. You want to know how much money you'll have after 10 years.
Step 1: Convert APR to decimal
APR = 3% = 0.03
Step 2: Determine compounding frequency
Compounding is monthly, so n = 12
Step 3: Calculate the final amount
Step 4: Calculate the total interest earned
Result
After 10 years, you would have approximately $7,106.25, earning $2,106.25 in interest.
This example shows how compound interest can significantly grow your savings over time. Even small amounts of money can accumulate into substantial sums with the power of compounding.
Frequently Asked Questions
What is the difference between APR and APY?
APR (Annual Percentage Rate) is the simple interest rate that the bank advertises, while APY (Annual Percentage Yield) takes into account compounding and other factors, providing a more accurate representation of how much you'll earn.
How often should interest be compounded in a savings account?
The more frequently interest is compounded, the more your money will grow. Most savings accounts compound interest monthly, but some may offer daily or annual compounding.
Can I withdraw money from a savings account without penalty?
This depends on the specific savings account terms. Some accounts allow unlimited withdrawals without penalty, while others may have restrictions or fees for early withdrawals.
How does compound interest work?
Compound interest means interest is calculated on the initial principal and also on the accumulated interest of previous periods. This causes your money to grow exponentially over time.
Is it better to have a high APR or a high APY?
A high APY is generally better because it accounts for compounding, giving you a more accurate picture of how much you'll earn. However, always compare the terms and conditions of different accounts.