The Trinity Study Financial Freedom Calculator

What makes this calculator different from the others? Well, it’s based on actual data from over 80 years of S&P 500 and US Government Bond returns. The historical results included in this calculator span from January 1926 to December 2009. The Trinity Study authors compiled the data in order to determine the ‘safe withdrawal rate’ (the amount you can safely withdraw from a retirement fund without it failing) of a number of portfolio mixes.

To my knowledge, this calculator is the only one based on actual market returns.

One important caveat is that the results are historical. That means that the results aren’t necessarily a roadmap for the future. The calculator simply simulates what would have happened (on average) based on the actual movements of the market between 1926 and 2009. I’ve written more about the study here.

*Chance of Portfolio Success: ‘Portfolio Success’ is defined by the retirement portfolio sustaining itself at your target withdrawal rate. Portfolio failure is when the fund is unable to be withdrawn from before the end of retirement, i.e. the fund goes to zero prematurely.

**Median End of Retirement Portfolio Value: This is what the portfolio value would be at the end of the specified retirement length, based on the median returns of the stock and bond markets across the data compiled by the authors.



  • How Long I Want to Retire For:
    This is the duration of the retirement, which is how long the portfolio is targeted at sustaining the withdraw rate. Note that the amount required for retirement doesn’t change whether you want to retire for 15 or 30 years. The success rate however, is affected. If the fund needs to service a longer withdrawal period, the success rate will naturally decrease.  The required amount to retire is actually a function of the withdrawal rate and the amount you want to spend annually. The reason that retirement length is not linked to the amount you need to retire is because of the expected market return in the long term. You’ll see when playing with the calculator that several fund combinations would have shown end of retirement values which significantly exceed the initial portfolio.
  • How Much I Want to Spend:
    This is essentially how much you want ‘pay yourself’ annually from your retirement account.
  • Risk Appetite (Withdrawal Rate):
    This is how much you’re willing to withdraw from your retirement account annually. This and how much you want to spend dictate your required retirement portfolio to retire. You’ll notice that the chance of portfolio success and end of retirement value is very sensitive to the withdrawal rate.
  • Portfolio Mix:
    This is the balance of investments in your portfolio. Stocks are representative of the S&P 500 Index (a stock linked to the movements of the overall S&P 500 movement). An S&P Index fund is typically considered conservative through the fact that it’s significantly diversified. Bonds are representative of US Treasury Bonds, these are widely known as among the most conservative investments available, hence the volatility and returns are typically lower than those of stocks. US Treasury Bonds are deemed so secure that they’re often equivocated with the ‘risk-free-rate’.