How to convince yourself to get rid of stuff (especially if you live in CA)

I helped some friends move into their new home over the weekend, and as always, moving became an opportunity to decide whether certain things were really worth moving. The broken grill that just needs an afternoon's woodworking to fix, the rusted recumbent bike bought with good intentions, the box full of leis and decorative sticks left over from a theme party, all become a little less benign when you have to load them into a truck and then figure out where they "go" in a new home. Some popular metrics for throwing it out: if you haven't used it in the last year, if you haven't used it since your last move, if you forgot you owned it. I hereby propose another metric particularly suited for those living in California: what it would cost you to get that space back by enlarging your dwelling.

First, figure out approximately what it would cost in dollars per square foot to increase your living space. From browsing Craig's List postings of comparable apartments, my current 400 square foot apartment could be upgraded at a rate of about $1.5 per square foot per month. Now compute the floorspace that the item consumes, multiply, and you have an approximation of the opportunity cost of that item in dollars per month. Translate this to years for added impact. To keep my new conga drums at 27" × 14" I'm giving up about $50 worth of floor space per year, which is a rate I'm comfortable with.

To compute this metric for stackable items such as books, divide this number by how deep the items are currently stacked in the way you are storing them, so as your bookshelf gets taller the storage of each book gets cheaper. It's cheating to compare it against the height of your ceiling directly. Add in the extra space wasted in storage. On my 3 layer bookshelf, the average 6" × 1" paperback stored vertically with 5" of wasted space in front of it is costing me $1.35 per year. That's more than I paid initially for some of these used paperbacks that I still haven't read after a few years of lugging them around. Out they go. If you are living with someone and they want you to throw something out, experiment with paying rent to them on it at the rate you get from this calculation.