Portfolio planning lab
Portfolio Growth & Crash Simulator
Model contributions, returns, dividends, fees, inflation, and historical market stress in one transparent projection.
Projection
Portfolio value over time
How this projection works
The model compounds monthly, reinvests an annually changing dividend yield, deducts management fees, and converts the result into today’s purchasing power using the inflation assumption. Historical scenarios apply simplified calendar-year market returns for comparison; they are not forecasts.
Decision guide
Use the projection to compare assumptions, not to predict a balance
The decision it supports
Compare contribution levels, time horizons, fees, inflation, and a defined market shock. The useful question is whether a plan remains workable under less comfortable assumptions, not which input creates the largest number.
Try a reproducible comparison
Use $10,000 for 20 years, with no monthly contributions, a hypothetical 6% annual market return, no separate dividends and zero inflation. At 0.20% annual fees the model gives about $30,882.56; at 1.00% it gives about $26,532.98. Only the fee changes. These are illustrative model outputs, not expected investment returns.
Load the lower fee example · Compare the higher fee
Then add inflation to both runs. The nominal balances stay unchanged, but their purchasing power falls. Change one input at a time so you can explain the difference.
Method
The model applies monthly contributions and compounding, reinvests the stated dividend yield, deducts the management-fee assumption, and discounts the result by inflation. Stress scenarios insert simplified historical calendar-year returns. They do not replay every daily price or trading cost.
Assumptions and limitations
- Returns, inflation, fees, taxes, and contributions can change; the model holds user inputs to a simplified schedule.
- Sequence risk matters. Two portfolios with the same average return can finish differently when losses occur at different times.
- Taxes, withdrawals, fund tracking error, currency effects, and personal circumstances are not modeled.
- Historical shocks are comparisons, not forecasts or worst-case guarantees.
Common mistakes to avoid
- Selecting a high return solely to make the target appear achievable.
- Ignoring inflation or assuming contributions never pause.
- Treating a smooth projection line as the path markets will follow.
- Comparing products without including their full recurring costs.
Continue learning: Long-term investing guides · Financial glossary
Check the context: SEC explanation of investment fees and expenses. The balances in our example come from this calculator and its stated assumptions; they are not SEC projections.
Print a free planning worksheet to keep the assumptions, outputs and review questions together. No account or payment is required; worksheet entries are not sent to Market Master.