FI Calc vs Flexible Retirement Planner

FI Calc is a free web calculator for evaluating retirement plans and withdrawal strategies with historical market data. It runs simulations from annual figures covering 1871 through 2024, compiled from Robert Shiller’s data set, while warning that historical results do not guarantee future performance. Users can model equities, bonds and cash, set rebalancing and changing allocations, and add wages, Social Security or extra withdrawals for future expenses. The calculator provides income projection, savings growth projection, withdrawal planning, Social Security modeling and scenario analysis. Simulations can be exported as CSV files for spreadsheet analysis. Inputs are processed in the browser; saved or shared calculations are encoded in URLs that may reach the hosting provider, services and recipients. Google Analytics may receive page URLs containing saved inputs. FI Calc does not automatically model taxes or required minimum distributions and currently has no Monte Carlo simulations. The free plan costs nothing.

Flexible Retirement Planner models retirement outcomes with Monte Carlo simulation and reports the probability that a plan succeeds. It runs 10,000 simulated paths spanning savings accumulation and retirement spending. Users can compare Stable, Flexible, and Conservative spending policies, test different assumptions, and use sensitivity analysis to see which inputs affect results most. The standalone version lets users save inputs and maintain multiple what-if scenarios, and it works offline. The planner includes income and savings growth projections, withdrawal planning, detailed tax modeling, and Social Security modeling. Standalone downloads are provided for Windows and Mac/Linux; the Windows version does not require Java. The planner is free for individual non-commercial use, and educators and trainers may use it for educational purposes. A voluntary contribution of any amount unlocks a personal-use license key. Commercial use, including by financial planners, is not authorized or supported. Its maker, Random Walk Ventures LLC, created it in 2006.