This calculator shows the risk/reward relationship and that steady contributions in an index fund over long investment horizons (10 years or more) can accumulate wealth even through periods of market declines. This calculator uses historical monthly returns from 1999 to 2021 to show how steady contributions in an index fund can accumulate over time. Enter a monthly investment, a start date, and an end date. This calculator assumes periodic investments in the QQQ which tracks the NASDAQ index.