What is the Investment Growth Calculator?
In short
A $5,000 investment at 8% compounded monthly grows to $54,679 in 30 years without adding anything. Add $200/month and it grows to $352,751, more than 6× as much. At 10% (S&P 500 historical average) the $352,751 becomes $551,285. Regular contributions matter far more than your starting amount; missing a decade of contributions costs roughly half your final balance.
This investment growth calculator projects how a portfolio grows from a starting investment plus regular contributions, compounded at your expected rate of return. It separates how much you contributed from how much the market earned.
How to use this calculator
- 1Enter your initial investment.
- 2Add a regular contribution and its frequency.
- 3Set your expected annual return and compounding.
- 4Choose the number of years and months.
- 5Compare contributions vs. returns in the chart and table.
The formula
- FV
- — Future value (final balance)
- P
- — Starting principal
- PMT
- — Periodic contribution
- r
- — Annual interest rate (decimal)
- n
- — Compounding periods per year
- t
- — Number of years
KalkWise simulates each month individually so that contributions, compounding frequency, and partial years are all handled precisely.
Worked example
The scenario
Begin with $10,000, invest $500 monthly, earn 8% for 25 years.
The result
The portfolio grows to $548,915, with contributions at the end of each month: $160,000 contributed ($10,000 plus 300 deposits of $500) and $388,915 from compound returns.
Common use cases
- Projecting a brokerage or index-fund portfolio
- Planning dollar-cost-averaging contributions
- Comparing how return rate affects long-term wealth
- Setting realistic long-term investing expectations
Limitations & assumptions
- Real returns are volatile; this uses a smooth average rate.
- Excludes taxes, trading fees, and fund expense ratios.
- Results are nominal and not adjusted for inflation.
Frequently asked questions
What return rate should I use?
What is dollar-cost averaging?
Index funds or individual stocks?
Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.