Compound Interest Calculator

Compound interest calculators will help you understand the future value of money you need to invest.

Whether you are looking to save for retirement, buy your dream house, or fund your aspirations? Our Compound Interest Calculator is here to help. With this powerful tool, you can easily calculate the growth of your investments over time and make informed financial decisions.

How to use this Compound Interest Calculator?

You can use this compound interest calculator to estimate how your money potentially grows when interest is added to both your principal and any interest already earned.

Current Principal: It refers to the initial amount of money invested or deposited.
Annual Contribution: It represents the additional amount of money that will be contributed to the investment or deposit each year.
Term: It denotes the length of time for which the investment will be held or the deposit will be maintained.
Estimated Interest Rate: It signifies the anticipated rate of interest that will be earned on the investment or deposit.
Compound Interest Frequency: It indicates the frequency at which the interest will be compounded, such as annually, quarterly, monthly, or continuously.
Start Date: It denotes the date on which the investment or deposit begins.
The results of the compound interest calculator show you how much money you may potentially earn by letting your money accumulate interest over time. The more time you have your money invested, the more interest you will earn, and the more money you will have in the end

What is compound interest?
How to calculate Compound Interest in a savings account?*
How Does Compound Interest Grow Over Time? An Example:
What are a few ways to earn compound interest on your investments in 2026?
What can influence compounding over time?
Conclusion

What is compound interest?

Compound interest is a powerful concept that plays a significant role in the world of investing and saving. It has the potential to turn even small amounts of money into substantial sums over time. Compound interest refers to the process of earning interest not only on the initial amount invested but also on the accumulated interest itself. In simple terms, it’s interest on top of interest, creating a compounding effect that accelerates the growth of your money.

When you use a compound interest calculator, you’ll get two key results:

Future Value (Total Amount): The future value represents the total amount of money you will have at the end of a specified period, considering the initial amount, the interest rate, the term, and the frequency of compounding. It takes into account the compounding effect over time.*
Interest Earned: The interest earned is the additional money you have gained through compound interest. It indicates how much your initial amount has earned in interestThis amount is the difference between the future value and the initial amount you invested.

How to calculate Compound Interest in a savings account?*

To calculate compound interest in a savings account, you can use the following compound interest formula:

Future Value = Principal * (1 + Interest Rate)^Number of Years

Example

Principal Balance: The amount of money you deposit into your savings account.
Annual Rate: The annual interest rate offered by your savings account.
Number of Years: How long you plan to keep your money in the account.

For example, if you deposit $10,000 into a savings account with a 5% annual interest rate and leave it there for 5 years with annual compounding, your balance would be calculated as:

Future Value = 10,000 × (1 + 0.05)^5 ≈ 12,762.80

In this case, the interest earned over 5 years would be about $2,762.80.

How Does Compound Interest Grow Over Time? An Example:

If you invest $10,000 at a 5% annual rate and compound annually for 10 years, your balance would grow to about $16,288.

That means roughly $6,288 of the total is interest, and a large share of that interest accrues in the later years as you earn interest on prior interest.

You can use the calculator to compare shorter and longer timelines with the same rate to see how much of the growth comes from time rather than new contributions.

What are a few ways to earn compound interest on your investments in 2026?

You can use the compound interest calculator to model how different income‑generating products might grow when interest or distributions are reinvested, rather than withdrawn.

High‑yield cash accounts: High‑yield cash accounts pay a variable APY on cash balances, and interest can compound when you leave it in the account. Public offers a High‑Yield Cash Account as one way to hold cash that earns interest.
Bonds: Bonds pay periodic interest, which you can choose to reinvest to support compounding. On Public, you can find access to Corporate, Treasury, and Municipal bonds, as well as bond‑focused products.
Treasuries: Treasuries are debt obligations issued by the U.S. government, including Treasury bills, notes, and bonds. They pay interest at market rates and are backed by the full faith and credit of the U.S. government. Public lists various Treasury securities that you can use as inputs when you model potential compounding in the calculator.
ETFs: Many ETFs distribute dividends or interest and can be used to build diversified exposure. Public offers a range of ETFs across different asset classes and strategies; you can use their yields or total‑return assumptions in the calculator.
Stocks: Some stocks pay dividends that can be reinvested, adding to your share count over time. Public provides access to thousands of listed stocks, including many dividend payers, you can research and then model in the calculator.
IRAs: Traditional and Roth IRAs are account types, and compounding depends on what you hold inside the IRA and how taxes apply. On Public, you can open a Traditional or Roth IRA and run long-horizon scenarios in the calculator using the same contribution and return assumptions.
Certificates of deposit (CDs): CDs are another type of savings account that offer higher interest rates, but they come with a fixed term, so you’ll have to keep your money invested for the full term to earn the full interest rate.
Money market funds: Money market funds are a type of mutual fund that invest in short-term debt securities. They offer higher interest rates than traditional savings accounts, but they also have some risk.
Real estate investment trusts (REITs): REITs are a type of investment that owns real estate. REITs can offer high returns, but they also carry more risk than other types of investments.

What can influence compounding over time?

Time horizon: Compounding has more time to build when returns stay invested over longer periods. If you enter 5-, 10-, and 20-year horizons using the same rate, you will usually see a larger share of the modeled growth show up in later years.
Contribution pattern: Ongoing contributions add new principal that can start compounding within the model. In the calculator, you can compare a $10,000 lump sum to $10,000 spread across monthly or quarterly contributions to see how the path and ending value differ under the same assumed rate.
Reinvestment assumption (interest and dividends): Reinvesting coupons and dividends increases the number of shares or units in the model, which might change future cash flows and ending value. You can run “reinvest” versus “take in cash” scenarios to see how that assumption affects long-horizon results.
Fees and borrowing costs: Ongoing fees and interest on margin reduce the portion of your return that can compound. You can adjust the rate you enter in the calculator lowering it by your estimated all‑in costs to see a more realistic picture of what might compound for you after expenses.

Conclusion

Understanding compound interest can help you see how time, rate, and reinvested earnings can change a scenario’s future value. With this compound interest calculator, you can compare how compounding looks across multiple asset types by adjusting time horizons, contribution patterns, and reinvestment assumptions.

You can research stocks, ETFs, Treasuries, bonds, high-yield cash accounts, and IRAs on Public and plug those details into the calculator. Signing up on Public.com can help you keep your scenarios all in one place.

FAQs

When is compound interest calculator for?

A compound interest calculator is a tool that can be utilized to forecast a potential future savings growth in savings accounts. Compounding (daily or monthly) involves adding the interest earned to the existing balance, and the following period’s interest is calculated based on the updated amount, rather than the original principal.

When is my interest compounded?

In a savings account with compound interest, the initial amount is increased by the interest at the end of each compounding period, which usually happens on a daily or monthly basis. The account balance grows as interest is added through calculations.

How do you calculate compound interest?

To calculate interest without a calculator, use the formula A=P(1+r/n)^nt, where:

A = ending amount
P = original balance
r = interest rate
n = number of times interest is compounded in a specific timeframe
t = time frame

The above content provided and paid for by Public and is for general informational purposes only. It is not intended to constitute investment advice or any other kind of professional advice and should not be relied upon as such. Before taking action based on any such information, we encourage you to consult with the appropriate professionals. We do not endorse any third parties referenced within the article. Market and economic views are subject to change without notice and may be untimely when presented here. Do not infer or assume that any securities, sectors or markets described in this article were or will be profitable. Past performance is no guarantee of future results. There is a possibility of loss. Historical or hypothetical performance results are presented for illustrative purposes only