Project your portfolio's future value with regular contributions. Compare nominal and inflation-adjusted returns side by side.
| Year | Contributions | Total Gains | Nominal Balance | Real Balance |
|---|
Enter your initial investment — the lump sum you're starting with today. Then add your monthly additions — the amount you plan to invest each month going forward. Set your expected annual return rate (use 7–10% for a stock-heavy portfolio, or 5–7% for a balanced portfolio), your investment period in years, and your estimated inflation rate.
The calculator shows both your nominal future value (the actual number in your account) and your inflation-adjusted value (what that money will be worth in today's purchasing power). The dual-line chart makes it easy to see the gap that inflation creates over long periods — a critical reality for retirement planning.
The future value of an investment with regular contributions uses this formula:
This shows why a $343,778 nominal balance after 20 years only has the purchasing power of about $190,363 in today's dollars — inflation quietly erodes nearly 45% of the value.
Many people focus only on the nominal return rate — the headline number. But what matters for your financial goals is real purchasing power. Here's why:
Key insight: To maintain purchasing power, your nominal investment return must exceed inflation. At 3% inflation, you need at least a 3% return just to break even. Returns above inflation are your real gains.
Future value is calculated as FV = PV × (1+r)^n + PMT × [(1+r)^n − 1] / r, where PV is the initial investment, r is the annual return rate, n is the number of years, and PMT is the annual contributions. For inflation-adjusted value, divide the nominal FV by (1 + inflation rate)^n.
The S&P 500 has historically returned about 10% annually on average before inflation (about 7% after inflation). A balanced 60/40 portfolio has returned roughly 7–8% nominally. Most financial planning uses 6–8% as a conservative long-term assumption. Your actual returns will vary based on your asset allocation, fees, and timing.
Inflation erodes purchasing power over time. A nominal 8% return with 3% inflation means your real return is only about 4.85%. For retirement planning, what matters is what your money can actually buy — not the number in your account. Always use inflation-adjusted figures when setting long-term savings targets.
A common guideline is to invest 15–20% of your gross income for retirement. Use this calculator in reverse: set a target balance, then adjust the monthly contribution slider until the projection reaches your goal. Remember to account for inflation — your target balance in future nominal dollars should be significantly higher than your current purchasing power goal.