This question is awfully vague. The amount one needs to have saved in order to retire comfortably depends upon his/her income from other sources (pension, social security, rental income, part time wages, etc.) and his/her income need in retirement. See budgeting links/articles below -
Vanguard Retirement Expense Worksheet
Retirement and Good Living Budget
How to Set a Retirement Budget
How to Budget for Unexpected Costs in
5 Expenses that may derail a
retirement budget (Bankrate.com)
In general, most Americans are behind in saving for retirement and do not have a firm grasp on the amount of savings that is required to supplement their other sources of income of a period of 30+ years. For the majority of American workers, retirement at age 55 is not realistically achievable. In fact, an increasing number of workers find it necessary to work to age 70 in order to maximize social security income benefits and to make up for lost time in building their nest eggs. To provide a more quantitative answer, see the following article link -
How Much for the 401(k)? Depends.(Center for
To test your preparedness, you may also wish to check out Nest Egg Guru's Retirement Savings and Retirement Spending Calculators.
Hope this information is useful.