Cfiresim Review: The Crowdsourced FIRE Simulator

It’s no secret that FIRE (financial independence/retire early) is a goal of mine. When it comes to planning it, retirement calculators are a super helpful tool. Usually, retirement calculators focus on the individual’s savings and spending plan- aka their budget.

There’s a new retirement calculator on the block, and it wants nothing to do with your budget. What?! cfiresim is a free retirement calculator. The name is a little weird- it stands for Crowdsourced FIRE simulator. It doesn’t focus on budgets at all but simulates your retirement plans all the same.

cFIREsim is a calculator that focuses more on the historical behaviors of the stock market than on your own budgeting prowess. That makes it appealing to people who are curious about the market’s effect on their chance of FIRE.

In their own words “cFIREsim uses historical stock/bond/gold/inflation data from 1871 to present and calculates how your portfolio would have fared throughout history. If you enter a 30 year simulation period, it will run your data for every 30 yr period in history.”

By running your data against stock market history, cFIREism tries to tell you your chances of going broke in retirement. It compares your investments against big historical stock market drops and tells you if you have enough saved to survive those levels.

For those interested in FIRE this is a great tool. It’s impossible to predict the stock market, of course. But by looking backward at what it has done, we can get a little bit of an idea for what it might do in the future.

cFIREsim’s core mission is to help those interested in FIRE have a realistic understanding of what their investments might do during their retirement. It helps paint a picture of exactly if and when you might be able to retire early.

The calculator is fairly flexible. You can input all the details of your investments, income, and spending plan to get the most detailed response possible, or you can just do the basic inputs to get a large overview of what FIRE will look like for your money.

The basic inputs are these:

  • Retirement Year: This refers to the year your retirement starts
  • Retirement End Year: This refers to the year your retirement ends
  • Portfolio Amount: This refers to the total amount of investable assets you own currently (both tax-deferred and post-tax)
  • Yearly Spending: This refers to your total annual expenses.


The focus on the stock market. Again, nothing is guaranteed, but this calculator does it’s best to understand the stock market’s effects on your savings.

The level of detail. cFIREsim covers a lot of ground and market history. This aids in trying to deliver you an accurate rate of success for your portfolio.

Crowdsourced. This whole thing is crowdsourced! Meaning that you can be an active and valuable part of the community.  There’s a forum you can ask questions in and receive more in-depth support, request changes to the calculator, and share your thoughts.


Taxes. It doesn’t distinguish between differently taxed accounts. Meaning if you have a tax-deferred account and a taxable investment account, you need to figure out your tax burden in retirement.

Withdrawal strategies. cFIREsim only works with a few strategies. You may find that the one you’re looking to go with is incompatible with the calculator.

Complicated to use. This is not the most user-friendly retirement calculator out there. Even those who are interested in FIRE and have used other calulators find this a bit mystifying. You have to come prepared to get something out of this calculator.

Overall, cFIREsim is a great tool to add to your financial tool belt. By itself, it won’t be enough to flesh out your FIRE plan, but it’s focus on the stock market makes it a valuable addition when planning your financial future.


Looking for more great articles on how I handle my money? Try these articles:

Why I Have Trouble Spending Money

How to Save for Vacation

How I’m Paying Off That $1,200 Credit Card Bill



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