So, a

recent thread over on Bogleheads got me thinking about

The Shockingly Simple Math Behind ER.

However, it still isn't all that simple on the calculation side, and people still get hung up on it when thinking about pre-tax, post-tax, employer added income, etc.

But couldn't you re-formulate the table as a percentage of expenses? It seems that would be way easier to calculate. Like:

95% savings rate = 19x expenses -> <2yrs

50% savings rate = 1x expenses -> 17yrs

35% savings rate = 0.54x expenses -> 25yrs

25% savings rate = 0.33x expenses -> 32yrs

10% savings rate = 0.11x expenses -> 51yrs

Then, the calculation is really easy: I spent $55k and saved $32k (as in, this amount somehow made it into my various retirement accounts). So, 32/55 = 0.58, which is about 25yrs.

Does anyone have the spreadsheet for the math to verify if you can reformulate it this way? Did I miss something? (Probably! Or someone else would have already done it this way!)