This is just a suggestion by US government !!!

Based on this suggestion, you should have 1.1M by 60 years old if you are making 100K annually.  Let's exclude all the taxes.  If we use 75% as your retirement income compare to your working income, you will need 75K annually.  Based on retirement withdraw guideline of 4%, you can get 44K a year.  If your SS income is 24K a year, you will have 68K which is 7K short.  So save up to 1.3M at 62 and start taking SS, you should be able to retire at 62 with 75% of your working income of 100K.