A more detailed method is to add up the monthly expenses your family will incur after your death. Remember to include the one-time expenses at death and the ongoing expenses, such as a mortgage or school bills. Take the ongoing expenses and divide by .07. That indicates you'll want a lump sum of money earning approximately 7% each year to pay those ongoing expenses. Add to that amount any money you'll need to cover one-time expenses, and you'll have a rough estimate of the amount of life insurance you need.
There are also a few different ways your claim will be settled depending on your policy. Actual Cash Value will reimburse you for the replacement cost minus any depreciation. Because the cost can vary so much over time when it comes to property, this kind of policy could mean the limit on your coverage ends up coming in significantly below the cost to repair or even rebuild your home.