Results are illustrative only and are not financial advice. Tax calculations are simplified and may not reflect your actual tax liability. Consult a qualified tax advisor for personalized advice. Past performance does not guarantee future results. Tax is modeled as an annual deduction on interest earned; actual treatment depends on account type (taxable, tax-deferred, Roth) and your bracket.
Results
Total contributed
$70,000
Interest earned
$36,639.02
Return
+52.3%
Growth over time
Year-by-year balance projection including contributions and compounded interest.
Growth breakdown
Year-by-year balance, contributions, and interest earned.
| Year | Balance | Contributions | Interest |
|---|---|---|---|
| 1 | $16,919.19 | $6,000 | $919.19 |
| 2 | $24,338.58 | $6,000 | $1,419.38 |
| 3 | $32,294.31 | $6,000 | $1,955.73 |
| 4 | $40,825.16 | $6,000 | $2,530.85 |
| 5 | $49,972.70 | $6,000 | $3,147.55 |
| 6 | $59,781.53 | $6,000 | $3,808.82 |
| 7 | $70,299.43 | $6,000 | $4,517.90 |
| 8 | $81,577.68 | $6,000 | $5,278.24 |
| 9 | $93,671.22 | $6,000 | $6,093.55 |
| 10 | $106,639.02 | $6,000 | $6,967.79 |
- 1$16,919.19
- 2$24,338.58
- 3$32,294.31
- 4$40,825.16
- 5$49,972.70
- 6$59,781.53
- 7$70,299.43
- 8$81,577.68
- 9$93,671.22
- 10$106,639.02
Investment Growth Calculator: Project Long-Term Returns
Key Points
- Project the future value of a portfolio with a starting balance, periodic contributions, and an expected return.
- Optional tax-on-interest and inflation views show real (not just nominal) outcomes.
- Time is the dominant variable — small advantages in horizon dwarf small advantages in rate.
How to calculate investment growth
Investment growth is the projected future value of a portfolio that combines an initial deposit, ongoing contributions, and a compounding rate of return. Unlike a savings account, an investment account's returns vary year to year, but over long horizons the average annual return is what matters most for planning.
- Enter your current portfolio value (PV) — what you have invested today.
- Add your recurring contribution (PMT) and how often you make it.
- Set the expected annual return — a ~7% real return is a reasonable long-term equity baseline (≈10% before inflation).
- Choose the horizon in years, then optionally apply a tax rate or inflation lens to see after-tax and real outcomes.
Worked example
Start with $10,000, contribute $500/month, earn 7% annually for 30 years. The portfolio grows to roughly $660,000 — about $190,000 of which is your contributions and $470,000 is compound growth. Cut the horizon to 20 years and the figure drops to $290,000. Time is the heaviest lever.
How to use it well
Use realistic return assumptions — 7% real return is a reasonable long-term equity baseline. Test multiple scenarios (good market, average, bad) to understand range of outcomes. Compare taxable vs tax-advantaged accounts side by side. Re-run the projection annually with updated balances and assumptions.
Limitations
The calculator assumes a constant return; real markets have volatile years that materially change outcomes mid-horizon. Sequence-of-returns risk (especially near retirement) is not modeled. Inflation projections are themselves uncertain. Treat the output as a planning baseline, not a prediction.
Project, then keep contributing
A clear projection makes it easier to stay invested through volatility — you can see the long arc above the day-to-day noise. Run it once a year, adjust if reality has diverged, then get back to contributing.
Frequently asked questions
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