Investment Calculator

It projects the future value of a lump-sum investment plus regular monthly contributions, compounded monthly using your expected annual return rate. Results show both the nominal balance (raw dollars) and an inflation-adjusted real value so you can see what your money would actually buy at that future date.

The S&P 500 has averaged roughly 10% annually (nominal) over the long run, or about 7% after a typical 3% inflation assumption. A diversified portfolio with bonds mixed in is often modeled at 6-8%. Use a lower figure, say 4-5%, for conservative or fixed-income-heavy allocations. These are estimates, not guarantees.

Inflation erodes purchasing power over time. The calculator divides your nominal balance by (1 + inflation rate)^years to express the result in today's dollars. At the default 3.2% inflation rate, $100 today is worth roughly $50 in real terms after 22 years, so the real balance shows what your final nest egg could actually buy now.

No. The calculator shows gross returns before taxes and fund expenses. To estimate net results, subtract your expected expense ratio from the return rate you enter, and factor in applicable capital gains or dividend taxes separately. A 1% expense ratio on a 7% gross return, for example, drops you to roughly 6% net.

The calculator converts your annual return r to a monthly rate using (1 + r)^(1/12) - 1. Each month, your contribution is added first and then the full balance (including that contribution) compounds at that monthly rate. This means contributions earn a full month of growth in the period they are added.