How To Calculate Your Financial Independence Number

Financial independence number

If you are pursuing financial independence and early retirement, you should have a financial independence number. If you have been on an FI journey for a while, this is nothing new to you.

The financial independence number is the amount of money you need to be able to live off the returns on your net worth without depleting your net worth. Once you have money in the bank equivalent to your financial independence number, you can call yourself financially independent for life because it does not deplete your net worth.

Before we get to how you calculate your financial independence number, we need to understand a few things first.

How much money will you spend?

Before we dive into the calculations, you need to find out how much money you will spend each month once you reach financial independence.

A good starting point is to find out how much money you spend per month at the moment. If you don’t have a budget where this is visible, try to give an estimate of how much money you spend every month everything included (e.g. housing, transport, clothes etc.).

Keep in mind that some costs go up once you achieve financial independence and perhaps retire early.

Multiply your monthly spending by 12 to find out what your required yearly spending is when you become financially independent.

As an example, I spend roughly $2,500 per month, which makes my yearly spending requirement $30,000.

What is your safe withdrawal rate?

Next up is your safe withdrawal rate. This is used in combination with your yearly spending to calculate your financial independence number.

Much has been written about the safe withdrawal rate. People usually don’t disagree with the concept of safe withdrawal rates, but they like to discuss the value that it should have.

The safe withdrawal rate is the percentage of your net worth that you can withdraw each year without running out of money before you die. It originates from a 1998 study called the Trinity study. This is where the 4%-rule comes from if you have ever heard about that.

The Trinity study argued that you should have a safe withdrawal rate of 4% by looking at returns from 1925 to 1995. In that time period, it would have been highly unlikely that you would have depleted your net worth if you had only withdrawn 4% every year. This is assuming that your net worth would still have been invested in a stock-dominated portfolio.

I personally use a 4% safe withdrawal rate, but others argue that you should be even more conservative such as using a 3% safe withdrawal rate.

Why do I use 4% then? Well, if it turns out that 4% withdrawal depletes my net worth, I will be fine with spending less or earning some more money for a while. Keep in mind that the safe withdrawal rate assumes that you don’t make any additional income apart from investment returns.

Which safe withdrawal rate should you use? I would suggest something between 3-4%, and you’ll be fine.

Calculating your financial independence number

Now to the grand finale! Using the two financial ingredients from this post, you’ll be able to calculate your financial independence number.

You can calculate your FI number using this equation:

Financial independence number = Yearly spending / Safe withdrawal rate

As an example, my financial independence number is:

$750,000 = $30,000 / 4%

My financial independence number is $750,000. Once I have a net worth of that, I am financially independent and I can stop working for the rest of my life. Easy as that!

Having a number makes financial independence much more tangible for most people. For me it is a great motivation to have a clear goal, and I religiously track my progress every month.

If you are curious, you can also use your savings rate to calculate time to retirement using my financial independence calculator.

Your turn: What is your financial independence number?

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  1. Hi Carl,

    As I recall, the Trinity study relies on a 50/50 split between stocks and bonds and a 0% tax on returns. Correct me if I’m wrong. So basically I have two questions.
    1. How do you incorporate taxes in your calculations?
    2. If you calculate based on net worth how does that compare to the 4% rule? Her I am especially thinking of including a pension in the net worth which one can’t get access to early and the value of a home which also cannot be liquidated easily.



    1. Hi Sune,

      You are absolutely right. The Trinity study has its flaws, and the bond/stock split and tax returns are some of them. I have read some critique of the 4% rule – one of my favorite posts is from Early Retirement Now that go through many of those points and end up with the suggestion of using a lower safe withdrawal rate than 4%, but not by a lot. They also do simulations with 100% stocks, and here the 4% actually does relatively well with 89-97% success rate depending on the time horizon of the retirement.

      To answer your questions:

      1. I don’t include taxes explicitly even though it would be more correct to do so. However, the negative tax effect might be offset by the (hopefully) higher returns of a full stock portfolio compared to the 50/50 split. There are many technicalities that you could tweak, but the 4% rule is for me just a guidance that is easy to communicate and aim for. In reality, you would need to make your own more precise calculations as you get closer to early retirement (for example, the 4% rule also assumes that you never work or have an income again, which I definitely will post-retirement). I am using my calculator on this site to calculate the exact time to retirement (which includes taxes, inflation etc.), but it is also just a guidance.

      2. Good question. Pensions in Denmark will be accessible at the age of 60-something and hopefully you can sustain yourself on the other parts of your net worth until then, but of course, it is something to keep in mind. Again, you would need more precise calculations as you get closer to early retirement and know how your life looks then. Home equity isn’t liquid and there’s much debate about whether to include it or not. In my case, I believe it can be liquidated relatively easily (it’s a central Copenhagen apartment – crossing fingers the market don’t crash too hard) if we need the money, since we can just sell it and rent instead, which we actually plan on doing later in life.
      In general, I don’t really think that much about whether I’m getting it exactly right with the 4% rule (of thumb). I believe there are arguments for (e.g. higher returns than the 50/50 split) and against (the arguments you mention). For now, I use it as a guiding principle and as I get closer to the 4.500.000 DKK, I will have to make more precise calculations – of course taking into consideration how my net worth is distributed across cash, stocks, peer-to-peer lending, cryptocurrencies, home equity, pension etc.

      Thanks a lot for the great questions – it is always good to be challenged on some core assumptions in key FIRE principles that most people (including myself) tend to ignore.


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