Putting together your retirement plan takes a bit of clairvoyance: You need to predict the future, or at least predict your future needs, so that you can save enough in the present.

Many people are unsure of exactly how to do this. A recent post at Free Money Finance by Todd Tressider offers six questions everyone should ask to figure out how much they need to save for those later years:

  1. At what age will you retire?
  2. How much will your company pension and Social Security pay out over the duration of your retirement?
  3. What will the growth rate of your investments be over the rest of your life?
  4. What will the inflation rate be during your retirement years?
  5. How much will you spend every year from the day you retire through the rest of your life?
  6. How long do you think you and your spouse will live?

As Tressider points out, some of these numbers can be difficult to come up with on your own. Some financial planners and online retirement calculators can offer answers using historical data — but don’t expect that average annual return rates will remain steady over the next 20 years, just because they had an average return of 8 percent in the past.

Tressider’s new book How Much Is Enough to Retire? offers advice on how to get these numbers more accurately, but a financial planner can also help you decide how much your need to save. At the very least, setting aside more than you think you’ll need may not be a bad idea.

What have you asked yourself when coming up with your retirement savings strategy? How old were you when you started saving for retirement?