I think the problem with the site is that it doesn't take into account non-traditional families. How do I figure one child and 3 adults (my mom lives with us... she consumes a heck of a lot more than a child would in terms of resources, but less with childcare)? We have dd in private school, which is about double our mortgage payment. We're older and are working much harder toward retirement than, say, a typical 24 year old couple with a baby and toddler would be. Building up your lives vs. preparing to coast. These little things make a huge difference that cannot be accounted for with standard calculations. I'm sure most people here are in similar situations where it really impossible to use a "rule of thumb" for living expenses.
Ultimately, these types of charts cannot take into account the nuances and that pretty much makes them moot. For example, I SAH (working only 15 hours a week when dd is in school), so I can cook from scratch almost every single day. Our food expenses are going to be much, much less than, say the single parent with one child even though there are less of them.
I just don't like these types of charts because it skews people's attitudes. Those that are making it work on less suddenly feel they need to earn more and those who are way over might suddenly feel that they have room to spend, when they don't in reality. Dh makes around 3 times what the chart says we need, but we don't live like that. Some people make under the number they give, but still manage to live quite comfortably. I think people just need to budget for their personal situations.
Edited by velochic - 4/24/11 at 7:13am