Arriving at a precise number can be complicated. And even then it isn't that precise, since no one can predict things like future inflation rates with any accuracy. However, this five-step process, based on one Consumer Reports devised some years ago, should get you closer:

1. Figure your family's current monthly living expenses. Unless you are an incredible saver, your total monthly take-home pay is probably close enough.
   
   
2. Estimate your family's future monthly expenses--assuming you, for example, are out of the picture. For most families, multiplying the number in line 1 by 75 percent will produce a workable ballpark figure.
   
   
3. Estimate your family's future monthly income. Include the surviving spouse's pay plus any reliable investment income, such as stock dividends. You may also be eligible for Social Security survivor benefits; see www.ssa.gov for details.
   
   
4. Subtract line 3 from line 2. This is your monthly shortfall.
   
   
5. Multiply the dollar figure on line 4 by the number of months your family will need the financial support that the life insurance provides. For example, if you wanted to provide that support until your newborn reached the age of 18, you'd multiply by 216 (that is, 12 months per year times 18 years).
   
   

The dollar figure you arrive at in line 5 is the amount of insurance your family would be likely to need simply to make up for the gap between their future expenses and future income. You may want to figure in some additional money to cover funeral expenses, the repayment of any debts (not including your mortgage, which is already accounted for under monthly expenses), and for your child's college education, which can be a big bill in its own right as we'll get to later.

If you already have some life insurance through your employer, you can subtract it from the total amount of insurance you need. However, in these times it's worth weighing how secure your job (and therefore that insurance) actually is.