Compound Interest Calculator
Calculate how your savings or investments grow over time with compound interest and regular contributions. Get instant results with growth charts and year-by-year breakdown.
Your Details
Enter your initial investment, interest rate, time period, and optional contributions, then click Calculate to see your projected growth with charts and year-by-year breakdown.
Final Balance
$0.00
Total Interest
$0.00
Total Deposits
$0.00
Interest %
0%
Investment Growth Over Time
Final Balance Breakdown
Annual Growth
Year-by-Year Breakdown
| Year | Start Balance | Contributions | Interest | End Balance |
|---|
Complete User Guide
What is Compound Interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest, it grows your balance faster over time because you earn interest on interest.
A = P(1 + r/n)^(nt)
A = final amount, P = principal, r = annual rate, n = compoundings per year, t = years
The more frequently interest compounds (e.g. monthly vs annually), the more you earn. This calculator also supports regular contributions to show how saving consistently boosts growth.
What Your Results Mean
Final Balance
The projected value of your investment at the end of the time period, including principal, contributions, and interest.
Total Interest
The total interest earned over the period. This is the growth from compounding (and from contributions earning interest).
Compound Frequency
How often interest is added (annually, monthly, daily, etc.). More frequent compounding yields slightly higher returns.
How to Use This Calculator
- Enter your initial investment (principal)
- Enter the annual interest rate and compound frequency
- Enter the time period in years
- Optionally add regular contribution amount, frequency, and timing (beginning or end of period)
- Click 'Calculate' to see your results
- Review the summary cards, growth chart, breakdown charts, and year-by-year table
Understanding Your Results
Growth Chart
Shows total balance and total deposits over time. The gap between them represents interest earned.
Final Balance Breakdown
Pie chart of how much of your final balance came from initial investment, contributions, and interest.
Rule of 72
Divide 72 by your interest rate to estimate years to double your money. At 7%%, money doubles in about 10 years.
Formulas Used
Compound amount without contributions:
A = P(1 + r/n)^(n×t)
With regular contributions, the calculator compounds each period and adds contributions at the chosen timing (beginning or end of period).
Important Notes
- This calculator is for educational and informational purposes only. It is not a substitute for professional financial or investment advice.
- Results are projections. Actual returns vary. Past performance does not guarantee future results.
- For investment planning, consider consulting a financial advisor.
Impact of Starting Late
Waiting to invest can mean:
- Less time for compounding
- Need for larger contributions to catch up
- Lower final balance for the same effort
Benefits of Compounding
Starting early and contributing regularly can:
- Grow wealth with less stress
- Let interest do more of the work
- Build a larger nest egg over time
Investment Tips
- Start investing as early as possible; time is your biggest advantage.
- Consistent small contributions can outperform large one-time investments.
- Reinvest dividends and interest to maximize compounding.
- Keep fees low; even 1% in fees can significantly reduce long-term returns.