There's no definitive answer to this question. Unfortunately, it isn't as easy as someone else doing some math, imputing data, and spitting out that x.xx% is a 100% guaranteed SWR. And even that wouldn't take into account what would happen if you have a major illness or other expense that you hadn't factored in.
I like to start at 4%, since that's what the various studies show as a solid WR (though that doesn't always account for a younger, longer retirement). Then I look at my life and think about factors that might make be above or below average.
Some aboves (meaning my chances for success are better, which would lead to a higher WR being "safe"):
Will have very solid health insurance, for life
Can very reasonably expect a large inheritance (but I don't factor in any specific amount when doing my math)
Have a very chubby budget so there's plenty to trim during down markets or high inflation
Plan to keep my tiny side hustle going indefinitely. It's easy, stress free, WFH, self-paced, and semi-enjoyable. It also creates a small inflation hedge and might be able to scale up as needed.
DH and I are totally willing to pick up some side hustles here and there if needed. Since earning even a few thousand $ a year will make a difference in a down market, this is huge.
We are smart and resourceful.
We don't have children or anyone else who relies on us financially, which decreases the chances of some types of unexpected expenses.
DH's inflation-adjusted pension
Etc.
Some belows:
No kids means we are 100% on our own. There will be no one to move in with us or move us in with them, or visit to help with tasks as we age. That means our chances of needing to hire out for things are higher, which means our budget is more likely to increase in later years.
We will be younger than average when we retire, which means more time our money needs to last.
Climate-change presents what I consider to be an additional level of unpredictability, not factored into the models.
etc.
Clearly, my list of Aboves is longer than my list of Belows, though neither here is comprehensive. That makes me feel pretty safe that we don't need to dip into <4% WR as we plan.
I think this is the kind of thinking everyone needs to do. Do you have children? Do you want to pay for college for them? What if those costs skyrocket even more? What if they excel at an activity and you want to be able to indulge that at a high (expensive) level? Do you have skills that would likely allow you to go back to at least some work, especially in the first ~5 years when SORR are the worst, even if it's during a recession and everyone else is looking for work as well? Is you budget large enough that there will be things you can easily cut for a few years when the economy is struggling? (It's much easier to trim things if you plan to spend $150k/yr and have a paid off house, than if you plan to spend $30k and have a house payment.) Will you resent having to do that? Would you consider any need to return to work as a failure, or it that just one basic component of your overall strategy?
Start asking yourself and answering these types of questions and you should get a decent sense of whether you are likely to be better or worst off than the average person, for whom "about 4%" is a solid, but certainly not foolproof, answer.
