A good guesstimate: 1. Figure out your current lifestyle expenses (you can track this over time if you use mint.com or other websites) 2. Subtract your mortgage if you plan to have it paid off by retirement 3. Add in fudge factors for healthcare expenses and increased or decreased discretionary expenses, depending on the lifestyle you think you will live

As with any planning, you can stare at the numbers forever and not feel satisfied. There is no one true answer.

Your lifestyle/spending in your 20s and 30s has little to do with your retirement lifestyle/spending. Especially if you're rasing children...

And is that an argument not to plan at all? Of course you can't pinpoint an exact figure, but it still pays off to plan even on a ballpark figure.

No....

I did not say don't plan at all, just think about the lifestyle you may have in the future, not the one you have now.

The firecalc page has a link to US averages [0]. I haven’t used it myself, so I count vouch for its utility.

[0] https://www.firecalc.com/real-cost-of-living.php

The normal optimistic number is a 4% yearly WD rate, so 25x yearly expenses saved. I’m a believer in no more than 3% withdrawal, so at least 33 years of expenses.