Compound Interest Calculator
Calculate how your money grows with compound interest. See the power of compounding with regular contributions and different compounding frequencies.
Formula:A = P(1 + r/n)^(nt)
Growth Summary
Future Value
$300,851
Total Interest
$170,851
131% return
Total Contributions$130,000
Effective Annual Rate7.23%
Time to Double~10.3 years
Initial Investment
Enter your starting amount
$
Monthly Contributions
Set your recurring deposit amount
$
Interest Rate & Time
Configure rate and compounding frequency
%
years
Growth Over Time
Visualize your investment growth
Year-by-Year Breakdown
Detailed annual projections
| Year | Start | Contrib. | Interest | End Balance |
|---|---|---|---|---|
| 1 | $10,000 | $6,000 | $919 | $16,919 |
| 2 | $16,919 | $6,000 | $1,419 | $24,339 |
| 3 | $24,339 | $6,000 | $1,956 | $32,294 |
| 4 | $32,294 | $6,000 | $2,531 | $40,825 |
| 5 | $40,825 | $6,000 | $3,148 | $49,973 |
| 6 | $49,973 | $6,000 | $3,809 | $59,782 |
| 7 | $59,782 | $6,000 | $4,518 | $70,299 |
| 8 | $70,299 | $6,000 | $5,278 | $81,578 |
| 9 | $81,578 | $6,000 | $6,094 | $93,671 |
| 10 | $93,671 | $6,000 | $6,968 | $106,639 |
Showing first 10 of 20 years
Compounding Frequency Impact
Compare different compounding options
| Frequency | Future Value | Total Interest | Difference |
|---|---|---|---|
| Annually | $284,670 | $154,670 | - |
| Quarterly | $297,755 | $167,755 | +$13,085 |
| Monthly | $300,851 | $170,851 | +$16,181 |
| Daily | $302,374 | $172,374 | +$17,704 |
The Power of Starting Early
See how time amplifies your returns
$106,639
After 10 years
+$36,639 interest
$300,851
After 20 years
+$170,851 interest
$691,150
After 30 years
+$501,150 interest
What If I Got a Different Rate?
See how interest rate changes affect your final balance
1.00%7.00%15.00%
Future Value
$300,851
Investment Milestones
100.0% complete
$300,851
of $100,000
2x
$20,000
Doubled your money!
3x
$30,000
Tripled!
5x
$50,000
Five times growth!
10x
$100,000
10x - Amazing growth!
Goal Achieved!
Congratulations on reaching your target!
2x
$20,000
3x
$30,000
5x
$50,000
10x
$100,000
Compare Investment Scenarios
See how different strategies affect your wealth
$
$
%
years
Investment Insights
2 insights based on your inputs
Long-Term Investor!
With 20 years, compound interest works hard for you. The last 10 years will earn more than the first 10 years combined!
Rule of 72
At 7% return, your money doubles every 10.3 years. In 20 years, you'll double 1 times!
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Future Value
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Frequently Asked Questions
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest, compound interest grows exponentially because you earn interest on your interest. This is why it's often called the "eighth wonder of the world."
More frequent compounding leads to higher returns. Daily compounding produces slightly more than monthly, which produces more than annual. For example, $10,000 at 5% for 10 years yields $16,289 with annual compounding vs $16,470 with daily compounding.
The Rule of 72 is a quick way to estimate how long it takes to double your money. Divide 72 by your interest rate to get the approximate years. At 6%, your money doubles in about 12 years (72/6=12). At 12%, it doubles in about 6 years.
Time is the most powerful factor in compound interest. Starting 10 years earlier can nearly double your final amount. A $500/month investment at 7% for 40 years grows to $1.2M, but for only 30 years, it's just $567K - less than half.
APR (Annual Percentage Rate) is the simple interest rate without compounding. APY (Annual Percentage Yield), also called effective annual rate, includes compounding and shows the actual yearly return. APY is always equal to or higher than APR.
How this works
Future value uses FV = P × (1 + r/n)^(n×t) + C × [((1 + r/n)^(n×t) − 1) / (r/n)] where P is starting principal, C is periodic contribution, r is annual rate, n is compounding periods per year, and t is years. Contributions default to end-of-period; switch to start-of-period for annuity-due math.
What this tool can’t do
When to consult a professional
This is a software engineering tool, not financial advice. Run the math here, then take the result to a certified financial planner, CPA, or your bank before making a decision that materially affects your money.
Sources
- [1]Consumer Financial Protection Bureau (CFPB)Official sourceconsumerfinance.govAccessed Apr 21, 2026
US consumer finance regulator; authoritative on mortgage disclosures, APR rules, credit cards.
Joseph OrdunaFounder & Software Engineer
Full-stack software engineer specializing in embedded systems, web architecture, and AI/ML. Founder of Practical Web Tools. Built the gesture-controlled drone IP acquired by KD Interactive (Aura Drone, sold on Amazon).
Growth Summary
Future Value
$300,851
Total Interest
$170,851
131% return
Total Contributions$130,000
Effective Annual Rate7.23%
Time to Double~10.3 years