Purchase Impact on FIRE Timeline Calculator

Calculate how much a one-time purchase impacts your FIRE timeline

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Plan for recurring monthly income over different time periods as well as windfalls and one-time purchases in the future.

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How will a major consumption purchase you make today impact your timeline to FIRE (Financial Independence / Retire Early)?

This simple calculator is designed to help you to answer the question of how a major consumption purchase like a vacation or new car impacts your timeline to FIRE. The results are surprising and thought-provoking. Your dream vacation may only add a few weeks to your FIRE timeline. On the other hand, buying that new BMW might mean working for an extra six months.

What is FIRE (Financial Independence / Retire Early)?

Financial Independence / Retire Early (FIRE) is a personal finance milestone where you have accumulated enough assets that the returns on your investments are enough to cover your cost of living. Once you have reached FIRE, you can live off the returns from your investments indefinitely and you have the freedom to spend your time however you like, without the need to work for income.

You don’t have to wait until age 67 to gain complete freedom over your time. Adjust the inputs on this calculator to see how soon you can reach FIRE and how much you need to accumulate to reach this milestone.

Using this calculator

This calculator makes it easy to understand how a major consumption purchase that you make today impacts your timeline to Financial Independence.

To use this calculator, simply fill in the inputs at the top of the page and click “calculate” to recalculate the impact your purchase has on your FIRE timeline.

  • Your current annual take-home pay is your post-tax income and does include any contributions that you make to retirement accounts like a 401k or HSA.
  • Annual spending in retirement is the amount you plan to spend each year in retirement. Note that in many cases, this number will be less your current spending, because (1) you will be covered by Medicare and (2) you may have paid off your primary residence, so you no longer have to pay a mortgage.
  • Current Investments is your total investments in the stock market. This would not include real estate equity.
  • Investment rate of return is the average return that you expect your investments to grow, not adjusted for inflation. This calculator uses 10% as a default Investment rate of return. Historically, the S&P 500 has returned on average 10% annually from its inception in 1926 to 2018.
  • Inflation rate is the average annual rate of inflation that you expect to experience in the future. Historically, the US economy has experienced an annual average inflation rate of 3%.
  • Safe Withdrawal Rate (SWR) is the estimated percentage of your net worth that you expect to withdraw to cover your living expenses in retirement. 4% is widely considered as the recommended SWR for retirement planning. This 4% withdrawal rate was found by the Trinity Study to have a 100% success rate over a 30-year retirement horizon with a 50% / 50% mix of stocks and bonds.

How do I calculate my FIRE number?

Your FIRE number is the amount of money you need to have invested such that the returns from your investments are enough to cover your ongoing living expenses. This number is based only on your estimated annual spending in retirement and your Safe Withdrawal Rate (SWR):

(FIRE number) = (annual spending) / SWR

The math behind the calculator

This calculator uses your input allocation percentages and rate-of-return for each to calculate a weighted-average rate-of-return for your net worth as it moves through the simulation.

At its core, this calculator uses the compound interest formula:

A = P * ( 1 + n)^t

Here A is the final amount, P is the principle (initial amount), n is the annual growth rate, and t is the time in years.

What about inflation?

Inflation is an important variable to account for when planning for retirement decades in the future. It is almost certain that we will experience inflation in the future, and for this reason having your money invested in assets and not all stuffed under your mattress is crucially important. Assets like stocks and real estate tend to rise with inflation while cash loses value, meaning the best way to preserve your wealth in times of high inflation is to be invested in these assets.

Don’t worry about inflation, it’s built-in to the calculator! This calculator accounts for inflation by subtracting the inflation rate (from the input slider) from the investment growth rate of return. This gives an inflation-adjusted rate of return which is then used to calculate your FIRE number and draw the graph. With this approach, all the numbers in the calculator are adjusted to be in today’s dollars. Think about it like this – you don’t have to worry about cost-of-living increases because it’s already skimmed off of your expected investment returns.