Build wealth through disciplined index fund investing. Test deposits, returns, fees, taxes, and inflation easily. See clearer projections before making smarter money decisions today.
This calculator models index fund growth month by month.
Gross effective annual return = (1 + r / m)m - 1
Net effective annual return = gross effective annual return - expense ratio - tax drag
Monthly rate = (1 + net effective annual return)1/12 - 1
Real balance = nominal balance / (1 + inflation rate)years
Recurring deposits are added at the beginning or end of each period. Annual contribution increases are applied once each new year.
| Initial Investment | Contribution | Years | Annual Return | Expense Ratio | Inflation | Estimated Ending Balance | Estimated Real Balance |
|---|---|---|---|---|---|---|---|
| $10,000.00 | $500.00 Monthly | 20 | 8.00% | 0.10% | 2.50% | $339,496.09 | $207,184.60 |
This example shows how steady investing can build a large portfolio over time.
An index fund compound interest calculator helps investors estimate future portfolio growth. It combines starting capital, recurring deposits, return expectations, and time. That creates a more realistic long term investing picture. Many people only look at raw returns. That can hide the impact of costs and inflation.
Compound interest means returns can earn more returns later. This effect becomes stronger as time grows. A small monthly deposit can become meaningful over decades. That is why disciplined investing often matters more than trying to time the market. Regular investing also reduces the pressure of making one perfect entry.
Index funds are popular because they offer broad market exposure. They are simple. They are diversified. They usually carry lower costs than many active choices. Lower costs can preserve more of your long term gains. Over long periods, that difference can become large. This page helps you test that effect directly.
Headline return is not the whole story. Expense ratios reduce net performance. Tax drag can lower growth in taxable accounts. Inflation reduces purchasing power. A portfolio may look strong in nominal dollars but weaker in real terms. That is why this calculator shows both ending balance and inflation adjusted balance. It also estimates drag impact.
You can compare monthly, quarterly, or yearly deposits. You can change compounding frequency. You can raise contributions every year to reflect income growth. That makes the projection more practical. A realistic plan is easier to follow. Use the yearly schedule to review progress. Use the graph to see how time and discipline work together. Then use the export tools to save your results for future planning discussions.
It estimates how an index fund portfolio may grow using a starting balance, recurring deposits, return assumptions, fees, taxes, inflation, and time.
Real balance adjusts the future amount for inflation. It helps you understand what the portfolio may be worth in today’s purchasing power.
Tax drag is the estimated annual reduction in return caused by taxes on dividends, distributions, or realized gains in a taxable account.
Expense ratio reduces net performance every year. Even a small percentage can noticeably lower ending wealth over long holding periods.
Yes. Use the annual contribution increase field. It raises each future year’s deposit amount and helps model salary growth or stronger saving habits.
It can matter slightly. More frequent compounding can increase the effective annual return, though long term contributions and time usually have bigger effects.
No. Markets are uncertain. This calculator provides estimates based on your assumptions, not guaranteed future performance or investment advice.
Choose beginning if deposits are invested right away. Choose end if contributions happen after the period’s growth has already occurred.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.