The Rule of 300

There are countless articles and calculators that will attempt to give you the best possible retirement advice and a projection of how long your money will last. But if you’re looking for the quickest and easiest way to figure out how much you’ll need to retire, then read on.

Pretty much every retirement calculator on the Internet is useless because the only two numbers that you need to look at are the amount of money that you spend during an average month — and the number 300.

After you figure out how much money you typically spend each month (You should already know this!) OR estimate the amount that you’ll need every month in retirement, multiply that number by 300. This is the amount of money you need in order to retire.

It’s that simple.

I made the table below so you could easily figure out the rough amount you’ll need in order to retire without even having to whip out your calculator. This applies equally to retirees of all ages ranging from 25 to 70+.

The Rule of 300

Monthly spending Amount needed to retire
$0 $0
$100 $30,000
$300 $90,000
$500 $150,000
$1000 $300,000
$2,500 $750,000
$5,000 $1,500,000
$7,500 $2,250,000
$10,000 $3,000,000

Where does your spending fall on this table?

Inherently, if you don’t spend ANY money in a normal month then you don’t need any money to retire. And conversely if you spend into the 5-digit range every month you’re going to need at least $3M to sustain your living habits.

This leave us with a necessary portfolio balance of $0-$3M. The amount you need in order to retire is completely up to you, and is dictated solely by your spending. The younger you are the more time you’ll have to reduce your lifestyle expenses, and optimize your current lifestyle to make 300x easier to accomplish.

How does this math work?

The formula for The Rule of 300 is very simple. It’s basically the 4% safe-withdrawal rate in reverse.

If you’re unaware of this term, The 4% Rule is a generally accepted estimation that allows you to withdraw 4% of your investment balance every year (adjusting annually for inflation). So, if you have $3M invested, you could take out $120,000 during the first year — in other words $10,000 per month.

Let’s do this equation out in long-form. First, we will start with a more modest family that spends $2,500 per month. To account for the family’s annual spending we need to multiply this number by 12 which equals $30,000. Now, to make sure they have enough to retire we need to multiply this value by 25 which brings us up to $750,000.

Now, they are able to withdraw 4% of this $750,000 portfolio in their first year which is $30,000. They can then divvy this money up by month. $2,500 per month (notice that this is the same amount we started with).

As time goes on the portfolio balance will continue to increase as the markets increase. And when utilizing the 4% Rule your portfolio balance should never bottom out. Ever.  So this means that if you had 300 times your monthly spending at age 20 it would last forever. It would work equally as well for someone retiring in their 40s, 50s or 60s.

Here is a calculation that shows the 4% rule in action:

We assume a 5% rate of return every year. Actually, we assume an 8% rate of return, but we remove 3% to adjust for inflation. This means that we can look at the cost of things in 20, 50 or 100 years in terms of today’s money. The graph above shows that the 4% rule will allow you to withdraw money comfortably for at least 100 years.

The 4% Rule could fail in turbulent economic conditions. But also take into account that as the economy grinds to a halt prices on goods will stagnate or drop. This allows you to effectively live on less while maintaining a withdrawal rate equal to your spending.

This simple math should give you a pretty good idea about how easy it can be to retire early. Generally, people are going to tell you they need millions of dollars to retire. But, you don’t need over $1M until you hit $3,333 per month in spending.

These calculations aren’t going to allow you to upgrade your lifestyle financially after you retire. They assume that you’re going to continue living a modest (or at least an equivalent) lifestyle for the rest of your life. These calculations also don’t take into account that you still have YEARS that you could earn more money (and probably will). A part-time job can offset the necessity of saving 300 times your monthly spending by a lot.


I’m not going to reinvent the wheel, so if you’d like more information about the 4% Rule, otherwise known as the “Safe-withdrawal rate”. Visit these fine sites:

jlcollinsnh – Stocks — Part XIII: Withdrawal rates, how much can I spend anyway???

MMM – The 4% Rule: The Easy Answer to “How Much Do I Need for Retirement?”

Investopedia – Four Percent Rule Definiton

Withdrawal calculator via BankRate: Savings Withdrawal Calculator

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