Investment Growth Calculator
Model how a portfolio grows with regular contributions and compound returns.
S&P 500 historical avg ≈ 10%
$777,333
6.9× your total investment
Total Invested
$113,000
Investment Returns
$664,333
Returns / Invested
587.9%
Monthly Withdrawal (4%)
$2,591
Formula
Projects portfolio growth with regular contributions and compounding returns.
A = P(1 + r)^n + PMT × [((1 + r)^n - 1) / r]
Worked Example
$10,000 starting, $500/month contributions, 8% annual return over 20 years:
- Starting balance: $10,000
- Total contributions: $130,000
- Final value: $344,000
- Investment gains: $214,000
Common Questions
What return should I assume?
Stock portfolios historically return 10%. Bonds return 5%. Diversified (60/40) return ~8%. Use conservative 7% for planning; actual returns vary yearly.
Does regular investing help?
Dramatically. $500/month for 20 years plus $10k upfront adds $130k but results in ~$344k. Dollar-cost averaging (regular investing) smooths market volatility.
Should I invest if the market might crash?
Time in market beats timing the market. Even investors who bought before 2008 crash recovered and profited by 2020. Stay the course.
Key Takeaways
- Consistency trumps timing—investing $500 every month automatically keeps you in the market instead of waiting for the "right" moment.
- A 2% difference in returns (8% vs. 10%) saves/costs $50k+ over 20 years—choose low-cost index funds.
- Start early; the first 10 years of contributions matter more than the second 10 due to compounding.