Which amount is correct? That depends. Consider two important variables:
While average life expectancy in the U.S. is around 79 years, many Americans will live beyond that. For example, for a couple aged 65 today, there's a 47% chance that either one of them could live to age 95. Will you outlast your savings if you live 25 or 30 years into retirement?
Will you travel? What about expenses to keep up a car or home? These costs can vary greatly for each household.
Let's do the math for something everyone needs—food. What would food costs mean to your budget if you planned on living on savings of $100,000 for 25 years? Using today's costs, a retirement age couple will spend roughly $588 monthly for food at home (or $3.22 per person, per meal). If you invested the money and earned 5%, you could withdrawal $578 monthly.2
Just buying groceries would eat up your whole budget and then some. This doesn't even account for dining out or splurging. Shocked? Does this sound comfortable to you?