@wtjbatman, thanks, and I agree with you :-).
@beltim, I see your point. I mainly referenced the MMM article so the OP could look at the table in the middle, which applies whether one is discussing early retirement or normal retirement. Comparing your description of your spreadsheet to MMM's table, it seems that you and he are different in what you calculate as the necessary savings rate. For example, a 10% savings rate in MMM's table results in 51 years to retirement, which starting at the age 30 you mention in one of your posts results in a retirement age of 81, which is not really a typical retirement age by any stretch.
I don't have a dog in this fight, really. You have your spreadsheet, MMM has his, they don't seem to line up. Since you're both probably proficient in Excel, the differences are probably in the assumptions. It doesn't matter to me because I don't plan on using either of them.
I did notice after reviewing MMM's article again that he has his spreadsheet there, for what that's worth.
Again, I would suggest to the OP that s/he look at a bunch of spreadsheets and ideally make his/her own. When one retires, whether early or not, should be one's own responsibility, and taking some random Internet people's advice as gospel without checking the math is probably not a good idea. (That's actually why I built my own spreadsheet.)