# Compound Interest Calculator

Estimate your savings or spending through compound interest. Enter your initial amount, contributions, rate of return and years of growth to see how your balance increases over time.

After 10 years, your total balance is \$29,542
After 10 years
your total balance is
\$29,542
Growth Over Time
Initial Amount
Total Contributions
Total Interest Earned
Totals by Source
Initial Amount:
\$5,000
Total Contributions:
\$18,000
Total Interest Earned:
\$6,542
Compound Interest Table
YearStarting BalanceAnnual ContributionsCumulative ContributionsInterest EarnedCumulative InterestTotal Balance
1\$5,000\$1,800\$1,800\$237\$237\$7,037
2\$7,037\$1,800\$3,600\$320\$557\$9,157
3\$9,157\$1,800\$5,400\$406\$964\$11,364
4\$11,364\$1,800\$7,200\$496\$1,460\$13,660
5\$13,660\$1,800\$9,000\$590\$2,050\$16,050
6\$16,050\$1,800\$10,800\$687\$2,737\$18,537
7\$18,537\$1,800\$12,600\$789\$3,526\$21,126
8\$21,126\$1,800\$14,400\$894\$4,420\$23,820
9\$23,820\$1,800\$16,200\$1,004\$5,424\$26,624
10\$26,624\$1,800\$18,000\$1,118\$6,542\$29,542

## What Is Compound Interest?

Compound interest is the formal name for the snowball effect in finance, where an initial amount grows upon itself and gains more and more momentum over time. It is a powerful tool that can work in your favor when saving, or prolong repayment for debts. Compound interest is often referred to as “interest on interest” because interest accrued is reinvested or compounded along with your principal balance. It is the interest earned on both the initial sum combined with interest earned on already accrued returns.

When saving and investing, this means that your wealth grows by earning investment returns on your initial balance and then reinvesting the returns. However, when you have debt, compound interest can work against you. The amount due increases as the interest grows on top of both the initial amount borrowed and accrued interest.

Compound interest is often calculated on investments such as retirement and education savings, along with money owed, like credit card debt. Interest rates on credit card and other debts tend to be high, which means that the amount owed can compound quickly. It's important to understand how compound interest works so you can find a balance between paying down debt and investing money.

### Simple Interest vs. Compound Interest

Simple interest is when interest is gained only on the principal amount. In this scenario, interest earned is not reinvested. If you were to gain 10% annual interest on \$100, for example, the total amount earned per year would be \$10. At the end of the year, you’d have \$110: the initial \$100, plus \$10 of interest. After two years, you’d have \$120. After 20 years, you’d have \$300.

Compound interest, on the other hand, puts that \$10 in interest to work to continue to earn more money. During the second year, instead of earning interest on just the principal of \$100, you’d earn interest on \$110, meaning that your balance after two years is \$121. While this is a small difference initially, it can add up significantly when compounded over time. After 20 years, the investment will have grown to \$673 instead of \$300 through simple interest.

You can use compound interest to save money faster, but if you have compound interest on your debts, you’ll lose money more quickly, too. Interest may compound on a daily, monthly, annual or continuous schedule. The more frequently the sum is compounded, the faster it will grow.

## How Compound Interest Works

Compound interest allows investments to work in your favor. The earlier you start saving money, the better. But the longer you take to pay off your compound interest debts, the higher they will become.

Compound interest is often compared to a snowball that grows over time. Much like a snowball at the top of a hill, compound interest grows your balances a small amount at first. Like the snowball rolling down the hill, as your wealth grows, it picks up momentum growing by a larger amount each period. The longer the amount of time, or the steeper the hill, the larger the snowball or sum of money will grow.

In terms of debt, compound interest can be like a pest problem. Let’s say you find two bed bugs in your room. You could get rid of them now, but instead, you wait a few days to take care of them. Then you discover that there are now dozens of bed bugs in your room. If you had taken care of the bed bugs right away, they wouldn’t have been able to multiply at such a rate.

With compound interest investments, it’s better to wait and allow these investments to grow, but with money you owe, it’s usually best to pay down debt as quickly as possible — especially if your interest rate is high.

### How Does Compound Interest Grow Over Time?

Compound interest can grow exponentially over time. For example, let’s say you invest \$500 at an 8% annual return. Over five years, this is how much cumulative interest you will earn if the interest is compounded monthly:

• Year one: \$42
• Year two: \$86
• Year three: \$135
• Year four: \$188
• Year five: \$245

## How to Calculate Compound Interest

With the compound interest formula, you can determine how much interest you will accrue on the initial investment or debt. You only need to know how much your principal balance is, the interest rate, the number of times your interest will be compounded over each time period, and the total number of time periods.

### Applying the Formula for Compound Interest

The compound interest formula is:

where:

• P is the initial principal balance
• r is the interest rate (typically, this is an annual rate)
• n is the number of times interest compounds during each time period
• t is the number of time periods
• A is the ending balance, including the compounded interest

To calculate only the compound interest portion (CI), the above formula can be modified by subtracting the initial principal (P):

where:

• CI is the compound interest earned

To calculate the ending balance with ongoing contributions (c), we add a term that calculates the value of ongoing contributions to the principal balance.

Where:

• c is the amount of the periodic contribution

### MoneyGeek’s Compound Interest Calculation

MoneyGeek’s compound interest calculator calculates compound interest using the above formulas. If you have selected monthly contributions in the calculator, the calculator utilizes monthly compounding, even if the monthly contribution is set to zero. If the contribution frequency is annual, annual compounding is utilized, again if the annual contribution is set to zero.

## How to Use MoneyGeek’s Compound Interest Calculator

The MoneyGeek compound interest calculator is simple to use and understand. Instead of using the compound interest formula, all you have to do is plug in your numbers and information about the interest. You can utilize this tool to determine how much you will owe in interest on your debt or estimate how much you will earn in interest on your investments.

### Enter Your Initial Amount

Start by entering the principal amount of your debt or investment. If you’re investing \$500, for example, type that number in the box.

### Set Monthly or Annual Contributions

This is how much you’re going to contribute to your investment or pay off your debt. For instance, if you’re investing an additional \$20 a year, enter that figure into the calculator and select “Annually.” If you plan to pay \$20 toward your debt each month, add that number and select “Monthly.” Try changing the dollar amounts up or down to see what happens to the ending balances.

### Estimate Your Rate of Return

This is where you enter how much compound interest you expect to receive on an investment or pay on a debt. If you have an 8% interest rate, you will enter that here. The rate of return on many investments is speculative, so entering an average number can give you an idea of how much you’ll earn over time. The rate of return you earn on your investments can make a big difference. See what the change in your balance is if you increase or decrease your rate of return by 1 or 2 percentage points.

### Set the Number of Years of Growth

Enter the number of years you plan to keep your money in an investment or how long you will take to pay off your debt. For example, let’s say you won’t touch your investment for five years, so enter five in that box. Try doubling your investment period: How much would you earn if you held it twice as long?

### Use the Bar Chart to Explore Growth Over Time

With the compound interest calculator, you can switch the view to see a comprehensive breakdown in different formats. The initial bar chart showcases how compound interest grows over time on top of your principal amount.

### Examine the Totals by Source Pie Chart

The MoneyGeek compound interest calculator uses a pie chart to show you the initial amount you contributed in purple, the total interest you earned in green and your total contributions in blue.

### Review the Table View

Just click the compound interest table on the right, and you’ll see each year, your starting balance, your annual contributions, cumulative contributions, interest earned, cumulative interest and total balance. You can even see how much you’d earn if you kept saving at that rate, or how much you’d be charged in compound interest if you wanted to pay off your debt.

## Frequently Asked Questions About Compound Interest

The rule of 72 is a formula you can use to see how long it will take for your investment to double when you factor in the rate of return. The rule of 72 can be used if you’d like to quickly estimate the ending balance without using the more complex compound interest formula. The formula is:

72 ÷ compound annual interest rate (without the %) = the number of years

Using the rule of 72, you would estimate that an investment with a 5% compound interest rate would double in 14 years (72/5).

Time value of money is a concept that money received right now is worth more than the same amount received in the future because of its potential to grow. This concept can be understood with a question: If someone was going to pay you \$100 today, how much more would they have to give you if they delayed the payment by a month? Because of the lost earning potential, you’d want more than \$100 in the future. Investors and economists often think about the time value of money as the risk-free return on money one could get over a period of time.

Because many investments do not pay a consistent interest rate, but are rather the average of a fluctuating market, the compound annual growth rate (CAGR) assumes compound growth over time to provide a projected rate of return.

This formula is the projected rate of return on an asset or investment, even if it does not explicitly pay compounded interest. The CAGR is a form of the compound interest formula, but rearranged algebraically to solve for the interest rate using the beginning balance, ending balance and number of periods.

Compound interest works against you if you have debts. The longer you take to pay off your debts, the higher your compounding interest will be, and you’ll end up paying back much more in the end.

With daily compound interest, you will earn (or be charged) compound interest every day. With monthly, you’ll earn (or be charged) interest each month, and with annual, you’ll earn (or be charged) every year. Due to the way the compound interest formula works, the more frequently you compound, the more interest earned (or charged).

You can look at your loan or credit card disclaimer to figure out if your interest is being compounded and at what rate.

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## Expert Insight on Compound Interest

MoneyGeek spoke with academic experts and industry leaders on compound interest to see what they had to say. The views expressed are the opinions and insight of the individual contributors.

1. What are some of the uses of compound interest?
2. What do volatility and rate of return have to do with compound interest?
3. How can compound interest affect you in a negative way (i.e., credit cards)?
4. How can it affect you in a positive way (i.e., savings and investments)?
5. If planning your savings using compound interest, how should you think about the rate of return/assumption to include in your plans?
David Hunter, CFA, M.E.C.

Chief Investment Officer at Rhame & Gorrell Wealth Management

Alexander Fleiss

Chairman and Chief Investment Officer at Rebellion Research Partners

Cicely Jones

Financial Planner, Certified Retirement Education Specialist

Steven Lewis

Investment Advisor Representative at Lewis and Associates Capital Advisors, LLC

James West

Professor of Economics and Business at Moravian University

Connor Oak

Senior Associate - Wealth Management at WorkOptional

Curtis Bailey, CFP, CRPC, EA, CFA

Financial Advisor at Quiet Wealth

Marshall Burroughs

Executive Vice President at M&R Capital Management, Inc.

Steve Hengehold

Certified Financial Planner and Retirement Income Certified Professional with HCM Wealth Advisors

Melissa Weisz, CFP®, CFA

Wealth Advisor & Associate Partner at Regent Atlantic Private Wealth

Bradley Huffman

Owner/Certified Financial Planner at Future Finances, Inc.

Sean J. Britton, MPA, NRP

Principal and Financial Planner at STAT Financial Health

Alan Robert Jung

Professor of Finance at San Francisco State University - The Lam Family College of Business

Jay Walker, Ph.D.

Assistant Professor at Old Dominion University

James M. Comblo, CFF, BPS

President and CEO at FSC Wealth Advisors, LLC

Gerald Loftin, J.D., CFP®

Principal at Proficient Wealth Counselors, LLC

Chuck Zuzak, CFP®, CFA®

Director of Financial Planning at JFS Wealth Advisors

Kyle Dodrill, CFP®

Investment Advisor at at Deschutes Investment Consulting LLC

Roger Gaddis, CPA, CFP®

Wealth Advisor and Senior Partner at Gaddis Premier Wealth Advisors

Justin Gabriel, CFP®

Financial Planning Manager at Pitzl Financial

Nicholas Ockenga, AIF®, CFP®

Financial Planner at Sentinel Group

Jeff Burke

CEO and Investment Advisor Representative at 7th Street Financial

Anthony Pascazio

Founder and Chief Executive Officer at Reedmark Advisors

Jake Heisler, CFP®

Financial Advisor and Principal at Quaker Wealth Management

Paul J McCarthy III

President at Kisco Capital

Michelle Rand, CFA

CEO at Cascade Investment Advisors, Inc.

Mark Kenney, CFP®, CTS™

Certified Financial Advisor at SHP Financial

Harold Zazula, CFP®, RICP®, CLTC

Certified Financial Planner™ and Retirement Income Certified Professional at Crystal Capital Management Corporation

R. J. Kelly, ChFC, CLU, CAP, RICP, MSFS, AEP, IAR, WMCP

Founder & Chief Visionary Officer at Wealth Legacy Group, Inc.

Timothy Malloy, MBA, CFP

Portfolio Manager

Tyron Draper, MBA, CFP®, ChFC®

Financial Advisor at Beacon Capital Management

Douglas R. MacGray

President at Stonecrop Wealth Advisors

Joe Taylor

Owner & Founder at Oak Street Advisors

Kevin Shuller, CFA, CFP®

Founder & Chief Investment Officer at Cedar Peak Wealth Advisors

Mike Wilson, CLU, ChFC

Founder at Blueprint Retirement Advisors

Clayton Johnson

Wealth Advisor at Squire Wealth Advisors

Ken Hopkins

President and CCO Orion Wealth Management LLC

Chris Hilyer

Founder and President at Heritage Wealth Solutions

Kevin Michels, CFP®, EA

President and Financial Planner at Medicus Wealth Planning

Leland Gross, CFP®

CEO of PeaceLink Financial Planning LLC

Colin Zizzi, CFP®, AIF®, CEPA®

Founder and Investment Advisor at Zizzi Investments

Miguel Delgado Helleseter

Associate Professor of Economics at California State University

Ensen Mason, CPA CFA MBA

Investment Manager at

Alexis Buchholz

Managing Partner at BFG Wealth Management

Howard Morin

Founder / Partner

Jude McDonough, CFP® AIF®

Senior Vice President | Wealth Advisor at Alliance Wealth Advisors

Tim Bauer, CFP®

Founder of Evergreen Financial Group

Jordan Bradford

Senior Financial Advisor

Zachary Jones

Investment Advisor, AIF®

Martin A. Federici Jr.

CEO of MF Advisers, Inc. & MF Tax & Accounting, Inc.

Gerald Hendrik

President at Rockwall Wealth Advisors

Jan Pevzner

CFP®, EA

Cody Moore

Wealth Advisor at Wealth Enhancement & Preservation

Nate Hoskin, CFP®

Founder & Lead Advisor at Hoskin Capital

Gregory Germain

Professor at Syracuse University College of Law

Jenifer Aronson

Managing Partner, CFA

Nathan Donohue, CFP®, RICP®, CLU®, CLTC®

Partner & Advisor at Consilio Wealth Advisor

Stuart Kruse, CFA

President and Founder at Kruse Asset Management

Dino Pagiazitis

Senior Vice President and Financial Advisor at Bridgeway Wealth Partners

Alex Okugawa CFP, CKA, CEPA

Financial Advisor at One Degree Advisors

S. Abraham Ravid

Sy Syms Professor of Finance, Sy Syms School of Business at Yeshiva University

Alex Caswell, CFA, CFP®

Wealth Planner at RHS Financial

James White Jr.

Wealth Advisor

Michael Parry

Director of Wealth Planning at Liberty Wealth Advisors

Sig Morriar Jr.

Founder and Executive Director at SPM Wealth, LLC.

Rachel Lauren

Cofounder and COO of Debbie

Chris Reilly

Founder at Mission Capital

Ross A. Runstedler

Insurance Broker & President of Runstedler Life & Retirement LLC

Dan Rooker, CFP®, CSLP®

Principal and Founder at Rook Financial LLC

Claire Hunsaker

Chartered Financial Consultant and Founder of AskFlossie

Brian Bristol

Founder & CEO at Pigeon Loans

Marcio Andrade

President of Fast Unsecured LLC

John McGee

Financial Advisor at High Point Financial Group LLC

Amotz Segal

Chief Revenue Officer and Board Member at Fintegra, Founder of Edge OMC

Ben Reynolds

CEO and Founder of Sure Dividend

Rakesh C. Gupta

Associate Professor of Management and Decision Sciences at Robert B. Willumstad School of Business at Adelphi University

Lisa Hanneken

Instructor of Accounting and Business at East Central College

Vrishin Subramaniam

Founder of CapitalWe

Catherine Harris

Financial Advisor and President at CHS Wealth Management & CPAs LLC

Jeffrey Clark

Wealth Advisor and Partner at Pine Grove Financial Group

Rahul Padhiar

Senior Financial Analyst at Chardan

Dalton Wu

Operations Analyst at Cornerstone PEO

Drew Blackston

Co-Founder, Certified Retirement Counselor® & Financial Advisor at Pearl Wealth Group

Brian Helmes

Senior Manager: Asset & Wealth Management Consulting

Matt Ahrens

Chief Investment Officer at Integrity Advisory, LLC

Dr. Michael Provitera

Professor of Organizational Behavior at Barry University

Andrew J. Tapparo

Founder of Tapparo Capital Management

Joshua A. Gerlick

Doctor of Management Fowler Fellow; Doctor of Management Nonprofit Management Fellow (Case Western Reserve University)

Larry Duffany

Principal Owner, Larry the Money Medic

Dr. Lisa Giddings

Associate Professor of Economics at the University of Wisconsin-La Crosse

Grant Aldrich

CEO and Founder

Arash Fayz

Co-Founder and Executive Director at LA Tutors 123

Jacob Tenney

Assistant Professor and Director of Financial Planning

Stacey Black

Lead Financial Educator