This calculator illustrates the cost of underperformance – or falling short of your target rate of return.
Specify the holding period for your investments and the value of your portfolio today. Choose a reasonable target or benchmark rate of return, and try different estimates for the ‘performance gap’ – the amount (in percentage) that actual returns fall short of the benchmark. The results will show that even a 1% performance gap over a long holding period will have a significant, negative impact on the future value of your investments.

With Benchmark Return 
With Benchmark Return less Performance Gap 
Future Value of Portfolio at the End of the Holding Period   
Assumptions
 A lower average return will mean less income tax  but for this calculation income tax is ignored.
 The difference in growth is based on the original amount of capital – no additional savings are assumed.
 It is assumed there are no withdrawals during the scenario.