Compound Interest Calculator

Visualize the power of compounding. Calculate your future wealth based on initial principal, monthly contributions, and interest rates.

Investment Parameters

$
$
%
Final Balance$47,931
Total Contributions$29,000
Interest Earned$18,931
Balance Growth Over Time
Final BalanceTotal Contributions
Annual Breakdown
YearContributionsInterestBalance
1$7,400$522$7,922
2$9,800$1,286$11,086
3$12,200$2,312$14,512
4$14,600$3,623$18,223
5$17,000$5,243$22,243
6$19,400$7,195$26,595
7$21,800$9,509$31,309
8$24,200$12,214$36,414
9$26,600$15,343$41,943
10$29,000$18,931$47,931

The Power of Compounding

Albert Einstein famously called compound interest the 'eighth wonder of the world.' It is the most powerful tool available to long-term investors, allowing small, consistent contributions to grow into significant wealth over time.

Our Compound Interest Calculator helps you visualize this growth with an interactive chart. By seeing the 'interest on interest' curve, you can better understand how time—more than even the amount invested—is your greatest asset in building a financial future.

Consistency Wins

Adding even a small amount every month can double your final result compared to just letting an initial deposit sit.

Time is Leverage

Starting 5 years earlier can result in hundreds of thousands of dollars in difference due to the exponential nature of growth.

Reinvesting Interest

By keeping your earnings in the account, those earnings start generating their own interest, creating a snowball effect.

Private & Secure

We understand that financial planning is personal. That's why our calculator runs entirely on your device. Your numbers are never uploaded, stored, or shared with third parties.

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Frequently Asked Questions

How does compound interest work?
Compound interest is the interest on a loan or deposit calculated based on both the initial principal and the accumulated interest from previous periods. It is essentially 'interest on interest,' which allows wealth to grow exponentially over time.
Monthly vs daily compounding difference?
Daily compounding results in slightly higher returns than monthly compounding because the interest is added to the balance more frequently, allowing it to earn interest itself even sooner.
How do contributions change results?
Regular monthly contributions significantly boost the final balance because each contribution starts earning compound interest from the moment it is added. Even small monthly amounts can result in large final sums over decades.
What rate should I assume?
Historical stock market returns (like the S&P 500) average around 7-10% annually before inflation. For conservative savings, use 1-4%. Always remember that past performance does not guarantee future results.
Is this the same as APR or APY?
APR (Annual Percentage Rate) is the stated interest rate. APY (Annual Percentage Yield) is the actual rate of return after accounting for compounding within the year. This calculator allows you to see how different compounding frequencies affect the final result.
Can I model inflation?
To account for inflation, you can subtract the expected inflation rate (usually 2-3%) from your expected interest rate. For example, if you expect 8% returns and 3% inflation, use 5% to see the 'real' purchasing power growth.
How accurate is the chart?
The chart is an accurate mathematical projection based on the fixed interest rate and contribution frequency you provide. Real-world market returns fluctuate year to year.
Is my data stored?
No. All financial calculations are performed locally in your browser. We do not store or track your initial investment, contributions, or calculated results.