How much you need for retirement depends on a lot of variables specific to you and your family.
However, a good rule of thumb to see if you're headed towards a "wishing well retirement" is to multiply your pre-tax income by your age and divide by 10.
For example, if you're 50 years old and make $200,000 year, you should have $1,000,000 already saved.
(50 x 200,000 = 10,000,000 / 10 = 1,000,000)
Like any rule of thumb, this does not take the place of a well-structured and well-thought-out financial plan. As always, consult your financial planner.