Interest Calculator for Savings Bank Account
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Reviewed by Calculator Editorial Team
This interest calculator helps you determine how much interest you'll earn on your savings bank account. Whether you're saving for a short-term goal or long-term investment, understanding how compound interest works can help you maximize your savings.
How Savings Interest Works
Savings accounts typically offer interest that compounds periodically, usually monthly or annually. The interest you earn is calculated based on the principal amount (your initial deposit) and the account's interest rate.
Types of Interest
There are two main types of interest in savings accounts:
- Simple Interest: Interest calculated only on the original principal amount. The formula is: Interest = Principal × Rate × Time
- Compound Interest: Interest calculated on the initial principal and also on the accumulated interest of previous periods. The formula is: A = P(1 + r/n)^(nt)
Key Terms
Understanding these terms will help you use the calculator effectively:
- Principal (P): The initial amount of money deposited into the account
- Interest Rate (r): The annual percentage yield (APY) or annual percentage rate (APR) offered by the bank
- Time (t): The number of years the money is invested or saved
- Compounding Frequency (n): How often interest is calculated and added to the principal (monthly, quarterly, annually)
Note:
Most savings accounts compound interest monthly. The calculator assumes monthly compounding unless specified otherwise.
Formula Explained
The formula for compound interest is:
Compound Interest Formula
A = P(1 + r/n)^(nt)
Where:
- A = the future value of the investment/loan, including interest
- P = principal investment amount (the initial deposit or loan amount)
- r = annual interest rate (decimal)
- n = number of times interest is compounded per year
- t = time the money is invested for, in years
The interest earned can be calculated by subtracting the principal from the future value: Interest = A - P
Worked Examples
Example 1: Monthly Compounding
If you deposit $1,000 at an annual interest rate of 3% compounded monthly for 5 years:
A = 1000(1 + 0.03/12)^(12×5) = $1,159.27
Total interest earned: $159.27
Example 2: Annual Compounding
If you deposit $5,000 at an annual interest rate of 2.5% compounded annually for 10 years:
A = 5000(1 + 0.025)^10 = $6,643.32
Total interest earned: $1,643.32
Comparison Table
| Principal ($) | Rate (%) | Time (years) | Compounding | Future Value |
|---|---|---|---|---|
| 1,000 | 2 | 5 | Monthly | $1,104.08 |
| 2,000 | 3 | 5 | Monthly | $2,214.07 |
| 5,000 | 4 | 5 | Monthly | $5,520.16 |
Frequently Asked Questions
How often does my savings account compound interest?
Most savings accounts compound interest monthly. Some high-yield savings accounts may offer daily or quarterly compounding. Check with your bank for specific details.
What's the difference between APR and APY?
APR (Annual Percentage Rate) is the simple annual interest rate, while APY (Annual Percentage Yield) includes the effect of compounding. APY is generally higher than APR because it reflects the actual interest earned over time.
Can I withdraw money from a savings account without penalty?
Most savings accounts allow unlimited withdrawals without penalty, but some may have restrictions or fees for excessive withdrawals. Check your account terms for specifics.
How does compound interest help my savings grow?
Compound interest means your interest earnings earn interest too. Over time, this "snowball" effect can significantly increase your savings balance compared to simple interest.