What is compound interest, and why does it matter?

Compound interest is when you earn interest on both your initial deposit and previously earned interest. This causes your savings to grow faster over time, making it a powerful tool for long-term financial goals.

How often is interest compounded in this calculator?

This calculator assumes monthly compounding, which is common for savings accounts and many other financial products in the US.

How can regular contributions affect my total savings?

Adding money each month increases your total balance and allows interest to compound on a larger amount, significantly boosting your long-term savings.

What do the “Final Balance” and “Total Interest” numbers mean?

Final Balance is your projected account value at the end of your chosen period. Total Interest is the amount earned beyond your own contributions.

Can I export my results for use in other programs?

Yes. You can copy your results, download them as a PDF, or export to Excel for further review or sharing.

What happens if I change the interest rate or contribution amount?

Adjusting the interest rate or monthly contributions will immediately update all calculations, charts, and breakdowns to reflect your new scenario. This lets you compare different savings strategies side by side.

Compound Interest Calculator

Calculate compound interest growth over time.

Calculator Inputs

Compound interest assumptions

Principal ($)

Annual rate (%)

Rate type:

Nominal annual rate. US banks often show APY.

Years (1–50)

Monthly contribution ($)

Compound frequency

Quick presets

Results

Growth summary

Final Balance

$145,180

Total Contributions

$48,000

Total Interest

$87,180

Effective APY (est.)

7.23%

Total growth

150.3%

vs. principal + contributions

Interest share of final

60.0%

Balance Growth Over Time

Projected balance by year

Contributions vs Interest by Year

Contributions and interest earned each year

Yearly Breakdown

First 15 years. Download full schedule for all 20 years.

Year	Balance	Contributions	Interest
1	$13,216	$2,400	$816
2	$16,664	$2,400	$1,048
3	$20,362	$2,400	$1,298
4	$24,327	$2,400	$1,565
5	$28,578	$2,400	$1,852
6	$33,137	$2,400	$2,159
7	$38,026	$2,400	$2,488
8	$43,268	$2,400	$2,842
9	$48,888	$2,400	$3,221
10	$54,916	$2,400	$3,627
11	$61,378	$2,400	$4,063
12	$68,308	$2,400	$4,530
13	$75,739	$2,400	$5,031
14	$83,708	$2,400	$5,568
15	$92,252	$2,400	$6,144

Disclaimer: This tool is for educational and estimation purposes only. Results are hypothetical; actual returns vary. Interest on savings and investments may be subject to federal and state taxes in the US. Consider inflation and your personal situation. This is not financial, tax, or investment advice. For decisions about savings or investing, consult a qualified professional.

How It Works

Here’s a step-by-step guide to using this calculator:

1. Enter Your Assumptions

Initial deposit ($10,000 by default): The amount you start with.
APR (Nominal) (7% by default): The annual interest rate. US banks often quote APY, but this field uses the nominal APR.
Number of years (20 by default): How long you plan to save and let your money grow.
Monthly contribution ($200 by default): The amount you’ll add every month.

You can also select account types such as high-yield savings, CD/term deposit, or Retirement savings to match your situation.

2. View Results

After clicking Calculate, you’ll see a summary of your projected growth, including:

Final Balance: Your total savings at the end of the period.
Total Contributions: The sum of all monthly deposits you make.
Total Interest: The amount your money earns through compound interest.
Effective APY: The estimated annual percentage yield, reflecting the effect of compounding.
Total Growth %: Your overall percentage increase compared to your starting amount and contributions.
Interest Share: The percentage of your final balance that comes from interest earned.

3. Explore Charts and Breakdowns

Balance Growth Over Time: Visualizes how your savings grow each year.
Contributions vs Interest by Year: Shows how much of your yearly balance comes from your deposits versus interest earned.
Yearly Breakdown (first 15 years): Lists your balance, contributions, and interest for each year. You can download the full 20-year schedule if needed.

4. Export and Share

Copy: Instantly copy your results for sharing or saving elsewhere.
Export PDF: Download a PDF version for your records.

Export Excel: Download your full schedule and calculations in Excel format for deeper analysis.

Understanding Compound Interest

Compound interest is the process where your savings earn interest not only on your original deposit (the principal), but also on the accumulated interest from previous periods. This can help your money grow much faster than with simple interest, which only earns interest on the principal.

Many people use compound interest to plan for long-term goals, such as building an emergency fund, saving for retirement, or comparing different types of accounts, such as high-yield savings or certificates of deposit (CDs). Understanding how contributions and interest work together can make a big difference in reaching your financial goals.

For example, if you deposit $10,000 into a high-yield savings account and add $200 each month at a 7% annual interest rate, compound interest shows how those regular contributions and the interest earned will accumulate over time. This calculator helps you visualize that growth and plan your savings strategy.

How This Calculator Helps

This Compound Interest Calculator is designed to help you see exactly how your savings can grow over time with regular contributions and compounding interest. By entering your initial deposit, annual interest rate (APR), number of years, and planned monthly contributions, you can quickly view:

Final balance after your chosen time period
Total contributions you’ll make
Total interest earned from compounding
Effective APY (annual percentage yield), showing your estimated real return
Total growth percentage
Interest share of your final balance

The calculator also provides detailed charts, a yearly balance breakdown, and export options, making it easy to track your progress and make informed decisions.