Compound Interest Calculator — Visualize Your Investment Growth [2026]
Enter principal, monthly contributions & rate, get a year-by-year growth table with total interest earned. Plan retirement or savings goals. Free online tool.
Investment Growth Summary
Year-by-Year Breakdown
| Year | Balance | Contributions | Interest | Growth |
|---|---|---|---|---|
| 1 | $17,055 | $16,000 | $1,055 | 6.6% |
| 2 | $24,695 | $22,000 | $2,695 | 12.3% |
| 3 | $32,970 | $28,000 | $4,970 | 17.8% |
| 4 | $41,932 | $34,000 | $7,932 | 23.3% |
| 5 | $51,637 | $40,000 | $11,637 | 29.1% |
| 6 | $62,148 | $46,000 | $16,148 | 35.1% |
| 7 | $73,531 | $52,000 | $21,531 | 41.4% |
| 8 | $85,859 | $58,000 | $27,859 | 48.0% |
| 9 | $99,210 | $64,000 | $35,210 | 55.0% |
| 10 | $113,669 | $70,000 | $43,669 | 62.4% |
| 11 | $129,329 | $76,000 | $53,329 | 70.2% |
| 12 | $146,288 | $82,000 | $64,288 | 78.4% |
| 13 | $164,655 | $88,000 | $76,655 | 87.1% |
| 14 | $184,546 | $94,000 | $90,546 | 96.3% |
| 15 | $206,088 | $100,000 | $106,088 | 106.1% |
| 16 | $229,419 | $106,000 | $123,419 | 116.4% |
| 17 | $254,685 | $112,000 | $142,685 | 127.4% |
| 18 | $282,049 | $118,000 | $164,049 | 139.0% |
| 19 | $311,684 | $124,000 | $187,684 | 151.4% |
| 20 | $343,778 | $130,000 | $213,778 | 164.4% |
What is Compound Interest Calculator?
How to Use Compound Interest Calculator
Enter your initial investment (principal), monthly contribution amount, annual interest rate, and the number of years you plan to invest. The calculator generates a year-by-year growth table showing your balance, total contributions, total interest earned, and growth percentage for each year.
How Compound Interest Calculator Works
Common Use Cases
- Planning retirement savings and estimating future portfolio value
- Comparing the growth of different investment scenarios (interest rates, contribution amounts)
- Understanding the impact of starting to invest earlier vs. later
- Setting monthly savings goals to reach a target portfolio value
- Visualizing how compound interest creates exponential wealth growth over decades
Frequently Asked Questions
What is compound interest?▼
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. This creates a snowball effect where your money grows faster over time. It is often called "interest on interest."
How often is interest compounded?▼
This calculator uses monthly compounding, which is the most common frequency for savings accounts and investment returns. More frequent compounding (daily vs. monthly) has a small but positive effect on returns.
What is a realistic interest rate to use?▼
For a diversified stock market portfolio, the historical average annual return is about 7-10% before inflation (S&P 500 averages ~10%). High-yield savings accounts offer 4-5% as of 2025. Conservative bond portfolios return about 3-5%.
How does starting early affect compound interest?▼
Starting early makes a dramatic difference. Investing $500/month starting at age 25 at 8% annual return would grow to about $1.74 million by age 65. Starting at age 35 with the same inputs would only reach about $745,000 — less than half.
Does this calculator account for inflation?▼
No, this calculator shows nominal returns. To estimate real (inflation-adjusted) returns, subtract the expected inflation rate (typically 2-3%) from your interest rate. For example, use 5% instead of 8% for a rough real return estimate.
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