As more and more would-be parents weigh up the cost of raising children the costs purported by the media seem to rise exponentially. How do analysts arrive at these costs and are they justified?

A Survey completed by the US Department of Agriculture shows that at a minimum each child will cost more than $100K to raise from birth to age 18. What intrigues me is the costs they are including in these surveyed results.

In accounting there is a term to describe expenses that have already been paid as a result of conducting the business and these are referred to as "sunk costs". I suspect that many of the costs they include here, especially the big ticket items are "sunk costs" - meaning parents would have been paying for these costs regardless of whether they had children or not.

Regardless of whether I had 2 children or not I would most likely have a 3-4 bedroom house as an investment. To include the difference between the cost of this house and the costs of keeping a 1 bedroom apartment is not the cost of raising children. The same can be said of vehicles. I would most likely run a 6 cylinder 4 door sedan rather than a 4 cylinder 2 door coupe anyway so the difference between the running of these two should not be considered as the cost of raising a child.

If this is how we quantify the cost of raising children we would have to use the same calculations for arriving at the cost of keeping pets.