Calculator Inputs
Example Data Table
These examples illustrate how different assumptions can change long-term outcomes.
| Scenario | Initial Investment | Recurring Contribution | Years | Start Price | Growth Rate | Estimated Ending Value |
|---|---|---|---|---|---|---|
| Starter Plan | $1,000 | $250 monthly | 5 | $40 | 6% | $19,500 |
| Balanced Plan | $2,500 | $500 monthly | 10 | $50 | 8% | $97,400 |
| Step-Up Plan | $5,000 | $750 monthly | 15 | $65 | 9% | $269,800 |
Formula Used
1. Periods per year: periods = frequency count for weekly, biweekly, monthly, or quarterly investing.
2. Periodic price growth: periodic growth = (1 + annual growth)1 / periods − 1.
3. Periodic contribution growth: periodic increase = (1 + annual contribution increase)1 / periods − 1.
4. Shares bought each period: shares purchased = contribution amount ÷ current asset price.
5. Reinvested dividends: dividend cash = shares held × price × periodic dividend rate, then dividend cash buys more shares.
6. Fees: period fee = portfolio value × periodic fee rate, then equivalent shares are removed.
7. Portfolio value: ending value = total shares × ending price.
8. Tax on gains: estimated tax = max(ending value − total invested, 0) × tax rate.
9. Real value: inflation-adjusted value = after-tax value ÷ (1 + inflation rate)years.
10. Average cost per share: total invested ÷ total shares accumulated.
How to Use This Calculator
- Enter any starting lump sum you want invested immediately.
- Add the recurring contribution you plan to invest every period.
- Select weekly, biweekly, monthly, or quarterly purchases.
- Set the investment horizon in years.
- Provide the current asset price and your expected annual growth rate.
- Optionally include dividend yield, annual step-up contributions, fees, taxes, and inflation.
- Choose whether contributions happen at the beginning or end of each period.
- Press the calculate button to display results above the form.
- Use the export buttons to save the summary as CSV or PDF.
Frequently Asked Questions
1. What does dollar cost averaging mean?
Dollar cost averaging means investing fixed amounts at regular intervals. You buy more shares when prices are low and fewer when prices are high, which can smooth entry prices over time.
2. Why does contribution frequency matter?
Frequency changes how often you buy, how quickly money enters the market, and how compounding builds. Weekly purchases usually spread timing risk more than quarterly purchases.
3. What is average cost per share?
Average cost per share is total invested divided by total shares accumulated. It helps you compare your blended entry price with the current market price.
4. Why include fees and taxes?
Fees reduce portfolio value every year, and taxes can lower what you actually keep. Including both gives a more realistic picture of long-term net returns.
5. What does inflation-adjusted value show?
It shows the future portfolio value in today’s purchasing power. This helps you judge whether growth is genuinely strong after rising living costs.
6. Can I model increasing contributions?
Yes. Use the annual contribution increase field to simulate raising investments over time, such as after salary increases or planned yearly savings boosts.
7. Are the results guaranteed?
No. The calculator uses constant assumptions for growth, dividends, fees, taxes, and inflation. Real markets move unpredictably, so actual outcomes can differ materially.
8. Is this tool a replacement for financial advice?
No. It is an educational planning tool. Use it to compare scenarios, then combine the results with your goals, risk tolerance, and professional advice.