Having $1 million or more in your retirement account is a feat that just over 3% of Americans have currently achieved, according to the Employee Benefit Research Institute. But even if this goal is achieved, the rising cost of living is weighing on the budgets of many retirees, leading some to wonder:How long will this money last?“

If your goal is to save $1 million for retirement, or you’re already there, here’s how long it could last, based on a popular retirement planning strategy.

How long will $1 million last using the 4% rule

The 4% rule has been around for a while and is a basic recommendation for how much you should withdraw from your retirement. In short, the 4% rule says you should:

• Withdraw 4% of your savings balance during your first year of retirement
• Adjust withdrawals in subsequent years to account for inflation

For example, if you have $1 million in your account, you will withdraw $40,000 in the first year. Then, if inflation increases by 2% the following year, you would increase the amount you pay yourself by 2%, which would give you $40,800. You continue to make these inflation adjustments each year throughout your retirement.

In theory, if you follow the 4% rule, your $1 million in retirement savings could last for 30 years, or until around age 90 if you start retirement at age 60.

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The 4% rule is not perfect

The problem with giving a general calculation of how long your specific retirement funds will last is that no rule will do it perfectly, including the 4% rule. Some disadvantages of the 4% rule include:

• It assumes that inflation is the only factor affecting your annual spending.
• It is based on an equal allocation of 50% stocks and 50% bonds in your portfolio.
• It assumes historical market returns, which are not guaranteed
• It does not include taxes or investment fees

For all its flaws, financial services firm Charles Schwab says it’s best to think of the 4% rule as a good starting point rather than a rigid formula.

Indeed, the performance of your portfolio, the length of your retirement, your budget, your health and your general expenses will differ from those of other retirees. Using a rigid formula is therefore not a perfect solution.

Talk to a financial advisor

So if the 4% rule isn’t airtight, what should you do to make sure your million dollars lasts as long as possible? One of the best things you can do is sit down with a financial advisor to define your specific retirement goals.

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You can find fee-only (no commission) fiduciary financial planners on the National Association of Personal Financial Advisors (NAPFA) website. Their fiduciary status means they are committed to legal and ethical standards to work in your best interests rather than their own.

A financial planner can help you decide how much to spend each year in retirement and help you make adjustments based on your taxes, investment income, Social Security payments and inflation.

This means you’ll likely need to be flexible with your retirement spending. This may mean withdrawing more money in some years, but reducing your withdrawal in other years, depending on the rate of inflation and the performance of your investments.

Regardless of how much you have saved before retirement, spending time with a financial advisor will help you determine an appropriate spending range during your retirement years, whether that lasts three decades or even longer.