Using the Solo 401k Plan CalculatorEnter your own information into our Solo 401k Plan calculator. You can easily change the inputs to see what the impact will be. Areas highlighted in red will need to be filled in in order for the calculator to produce meaningful results. Produce a full detailed report to see a year-by-year break down of your Solo 401k account balance, cumulative contributions, investment earnings, and maximum allowable contribution. Also check out our many other 401k planning calculators including the 401k withholding calculator which shows how changing your 401k contributions affects your net take pay.