One of the rules of finance is: The rules are often changing, though in subtle ways, and a good example might be the old command of 4% when it comes to retirement savings.
If you can keep your retirement spending to just 4% of your savings, as long as you have at least some income you can make your savings last quite a number of years.
That's the rule, but it turns out to be a flexible one: Financial advisor Bill Bungen, who came up with the rule 30 years ago, now says you can move that rule up to 4.7%.
And it turns out that 30 years ago people weighed their portfolios in ways that are different from today, so the calculation should change.
Back then savers would put half their money in stocks and half in bonds, but that's all changed and a more balanced portfolio is called for.
But one of the other top rules of retirement is: Everyone's situation is different.
"It depends on every individual's circumstances, how much money they have, how long their lifespan is likely to be, and so on," says Cotton Wealth Management President Tom Cotton.
"I think as long as you stay under four-point-seven-percent of your savings, it is gonna be sustainable in most cases but it really depends on your individual circumstances and that's kind of on a case-by-case basis."