So we’ve all heard that “if you save and invest ‘X dollars’ every year starting at ‘age Y’ you’ll be a millionaire”.  How much will your retirement nest egg amount to at age 45? 55? 65?  Find out in seconds through this predictive simulation calculator!


  1. Click “Run Pen” to activate the interactive Pen
  2. Once activated, enter your current age, starting balance, and yearly contribution
  3. Click “Simulate Again” for a new simulation

The assumptions are as follows:

  • Rate of Return is calculated via =norm.dist(RAND(),mean,std dev) function to help simulate variability
  • Annual return is normally distributed with a mean of 1.06 (6% annual gain) and .13 standard deviation (95% (+/- 2std dev) of all years will be between -20% and +32%)
  • In today’s dollars, 6% real return as n approaches infinity
  • n = 50 simulations
  • Percentiles will create a decent interquartile range
  • Front-loaded annually

If you notice errors or have any questions or comments, please contact me here.

Happy Simulating!

  • rand() function inspired by MITx SC0x – Week 6, Slide 16
  • DISCLAIMER: This calculator is only a rough estimation, and not a crystal ball into the future.