CashCalc

Calculator

Compound Interest Calculator

See how your money grows over time with compound interest. Adjust the inputs to explore different scenarios and understand the power of compounding.

Getting Started

1.Enter your regular contribution amount
2.Set your expected annual interest rate (average stock market return is ~7-10%)
3.Experiment with different scenarios to see how small changes compound over time

Input Your Details

Regular Contribution Amount

Amount you'll add regularly (optional)

Annual Interest Rate

Expected annual return (e.g., 7% for stock market average)

Initial Investment (Principal)

The amount you're starting with (max $10,000,000)

Time Period

years

How long you'll let your money grow (1-50 years)

Compounding Frequency

How often interest is calculated and added to your balance

Contribution Frequency

How often you'll make contributions

Contribution Timing

When contributions are made each period

Your Results

Final Balance

$609,985.50

Effective Annual Yield: 4.15%

Initial Principal

$0.00

0.0% of final balance

Total Contributions

$180,000.00

29.5% of final balance

Interest Earned

$429,985.50

70.5% of final balance

Composition of Final Balance

ContributionsContrib.

InterestInt.

💡 Power of Compounding

→ Your interest earned ($429,985.50) exceeds your contributions ($180,000.00)! This is compound interest at work.
→ Your investment has more than doubled through compound interest alone.
→ Starting early matters: even small contributions can grow significantly over time.
→ Your effective annual return is 4.15%, accounting for both growth and contributions.

Growth Over Time

This chart shows how your balance grows over time, broken down by contributions and interest earned.

Year-by-Year Breakdown

Year	Balance	Contributions	Interest
1	$6,196	$6,000	$196
2	$12,841	$6,000	$644
3	$19,965	$6,000	$1,125
4	$27,605	$6,000	$1,640
5	$35,796	$6,000	$2,192
6	$44,580	$6,000	$2,784
7	$53,999	$6,000	$3,419
8	$64,099	$6,000	$4,100
9	$74,929	$6,000	$4,830
10	$86,542	$6,000	$5,613
11	$98,995	$6,000	$6,452
12	$112,347	$6,000	$7,353
13	$126,665	$6,000	$8,318
14	$142,018	$6,000	$9,353
15	$158,481	$6,000	$10,463
16	$176,134	$6,000	$11,653
17	$195,063	$6,000	$12,929
18	$215,361	$6,000	$14,297
19	$237,125	$6,000	$15,765
20	$260,463	$6,000	$17,338
21	$285,489	$6,000	$19,025
22	$312,323	$6,000	$20,834
23	$341,097	$6,000	$22,774
24	$371,951	$6,000	$24,854
25	$405,036	$6,000	$27,085
26	$440,512	$6,000	$29,476
27	$478,553	$6,000	$32,041
28	$519,344	$6,000	$34,791
29	$563,084	$6,000	$37,740
30	$609,986	$6,000	$40,902
1	$6,196	$196
2	$12,841	$644

29	$563,084	$37,740
30	$609,986	$40,902

Understanding Compound Interest

What is Compound Interest?

Compound interest is when you earn interest on your interest. Each period, the interest earned is added to your principal, and the next period's interest is calculated on this new, larger amount. This creates exponential growth over time.

Why Does Frequency Matter?

The more frequently interest compounds, the faster your money grows. Daily compounding will result in slightly more growth than monthly or annual compounding, even with the same annual rate.

The Power of Starting Early

Time is your greatest advantage with compound interest. Starting to invest early—even with smaller amounts—can result in significantly more growth than investing larger amounts later, due to the exponential nature of compounding.