How much life insurance to own?

One method that can be used is called the "human life value" approach. This is calculated as the present value of the family's share of the deceased breadwinner's future earnings. It is calculated as follows:

a) Estimate the individual's average annual earnings over his or her productive lifetime
b) Deduct taxes, insurance premiums and the cost of self-maintenance; the remainder is used to support the family
c) Determine the number of years from the present age to the retirement age
d) Use a reasonable discount rate the determine the present value

For example:
present age: 30
retirement age 65
annual earnings $50,000
self maintenance: $20,000
support family: $30,000
present value for 35 years at 4% discount: 19.41
amount to insurance needed: $582,000

This is slightly more than 10 years. For such a large sum, it is necessary to buy decreasing term insurance.

If the period is taken as 25 years (i.e. the children would have grown up), the factor is 16.24. The amount of insurance needed is $487,000. This is close to my rule of thumb of 10 years.