The pandemic has been a financial wake-up call for many and it has caused them to rethink their plans around work and retirement. 

In a recent report, 36%, of Americans said that they will never have enough money to be able to retire.

Even more — roughly 41% — said their ability to be financially secure in retirement would “take a miracle,” according to the Natixis Global Retirement Index.  

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To be sure, the Covid crisis has taken a hefty toll on retirement security in the U.S.

For starters, the economic downturn set retirement savers back, while low interest rates, higher inflation and ongoing market volatility are posing problems for long-term financial security.

Yet most people still want to retire as soon as possible. The average retirement age at which Americans say they plan to stop working is now just 62.

That raises the stakes for most Americans’ need to pinpoint how much money they will need and how long that money can last.

There are a few simple rules of thumb, such as saving 10 times your income by retirement age, although experts recommend using a retirement calculator to get a more accurate picture of your retirement number.

Still, the old rules may no longer apply.

“There’s not necessarily a one-size-fits-all solution,” said Christopher Schreiner, a certified financial planner and chief operating officer of Reston, Virginia-based Mason Investment Advisory Services, ranked 13th on CNBC’s 2021 FA 100 list.  

“Spending will always be the most important variable,” he said for retirees. “The perfect investment solution can’t overcome someone spending beyond their means.”

Further, there is a good chance your health-care costs will be higher than expected now, too. Especially if you retire before becoming eligible for Medicare at age 65. 

For years, financial advisors have also relied on the so-called 4% rule for retirement income: Retirees can withdraw 4% of their total portfolio every year to live on, while maintaining an account balance large enough to last for 30 years.

However, a longer retirement amid so much economic uncertainty puts that standard to the test as well.

“A 35-year time horizon with interest rates at historic lows could make 4% more challenging,” said Matthew Young, president and CEO of Naples, Florida-based Richard C. Young & Co., ranked No. 5 on CNBC’s FA 100 list. “I tell clients you might want to consider 3%, just in case.

“We just don’t know what type of environment we are going to have in the next 15 years in terms of returns,” Young said.

Even the typical view of asset allocation has changed.

Steven Check, president of Check Capital Management in Costa Mesa, California, which ranked No. 4 on the CNBC FA 100 list, recommends sticking with an 80% allocation to stocks — even an S&P 500 index fund — for someone retiring at age 65. Year to date, the S&P 500 stock index is up 16%, and roughly 30% over the past 12 months.

“This is higher than what you’d normally see recommended, but it would have worked fine historically, and I think it is even more necessary with interest rates so low,” Check said of a portfolio heavily weighted toward stocks and stock funds versus a more traditional retirement portfolio heavily weighted in bonds and cash.

“Projected returns aren’t going to be as good as they were because of stock valuations and bond yields,” he added. “The models that are based on past returns can’t be projected forward.”

Check also recommends a “two-bucket” approach, keeping roughly five years of spending money on hand in stable, liquid assets such as money-market funds and short-term bonds, and the rest invested in stocks for long-term growth.

Even if you spend 4% of your assets in year one (and increase this by 3% each year for inflation), then your money would last 35 years, he said.