The One Week Rule

During my last year at college, we all talked about getting our first real apartments (as opposed to the ones we had while we were at school). The apartments we were going to pay for with the salary from our first real (translate as "career") job. We all knew you had to follow the one week rule. Looking back, I'm fascinated that we all knew this rule, but in retrospect we don't know where we learned it. It was just there. Passed along by word of mouth, and somehow taken in by osmosis. It's that actual teaching process that now interests me, as I'd like to make sure we restore it.

What is the one week rule? Basically, it's this: your monthly rent should not exceed one week's salary. That's it. If you make $500 a week, you can afford a $500 a month apartment. This is very simplistic, but for any good rule of thumb to work, it needs to be very simple.

The one week rule works equally well for determining how much house you can afford. Actually, the one week rule it turns out, is what lenders call the front-end ratio. The front-end ratio is the percentage of your income used to make mortgage payments. It's calculated by dividing your monthly housing expenses (principal, interest, taxes and insurance or "PITI") by your monthly gross income. So, going back to the one week rule, this should be about 25% of your monthly income.

This is all pretty simplistic. There are other factors out there, like car payments, credit card payments, etc. that have to be considered (these make up what lenders call the back-end ratio). Ever see the episode of the Cosby Show where Cliff pretends to be the landlord to teach Theo a lesson about money? In short, you can't spend your whole paycheck on rent. Anyway, simple as it is, I think the one week rule is a very good starting point for deciding how much you can afford to spend on housing.

Here's my question, how did we all magically learn the one week rule? When did people stop learning it? How do we get back on track, and start passing it on to our children? If you learned a rule of thumb similar to my one week rule, what was it, and where did you learn it? I'd to love to hear about it and share it.