Bus Tickets Cost a Lot

Personal-finance gurus tell you to spreadsheet every single income and expense, tagging them all by category—because more data is better, right?

I, for one, can't be bothered. Instead, I've created a hella-low-maintenance spreadsheet in which I pay myself a weekly allowance of ₩100,000 ($90) and track my spending against my predicted account balance.

I only update my spreadsheet with three events:

  • Every month, I input my pay, which varies slightly because my school deducts my cafeteria lunches.
  • I make a note in another column every time I transfer money to the US.
  • Every half month, I note my account balance.

A function then computes my target account balance—the amount of money that would be in my account if I spent my weekly ₩100,000 allowance and nothing more.

Because my school pays directly for my housing and most food, the only nonnegotiable expenses that have to come out of this allowance are my phone plan (₩46,000 a month) and my transportation (maybe ₩15,000 a week). A true spreadsheet fetishist would log these as well and reduce the weekly allowance accordingly. But such scrupulous data entry would consume time I'd rather spend writing pithy blog posts.

From my semimonthly account balances, I subtract the target balance for the corresponding days to produce the following graph.

Here's how you read it: If I spend exactly ₩100,000 a week, then my account balance will parallel my target balance and the graph will flatline. If I stay under budget, the blue line goes up; if I overspend, it goes down. I'm tracking the difference between my target and actual balances, rather than their absolute values, to mitigate the spending impulse that comes from watching my account balance spike when my monthly pay comes in.

Even if the graph falls below zero, I'm not immediately losing money; I'm just saving less. Conceptually speaking, you can view as the graph of my additional savings on top of what I already save by implementing the allowance in the first place. In other words, it's showing the current balance of my allowance account.

You can see that I remained pretty frugal during my first few weeks here, then started to spend more around mid-October. In fact, I made two weekend trips to Seoul, and bus tickets and hotels cost a lot. But my position is still north of zero.

For what it's worth, the trend line shown, a least-squares regression courtesy of Google Sheets, is somewhat meaningless. This graph isn't predictive in nature, unless you're one of those in a deterministic universe, there's no such thing as free will zealots. Instead, I use the graph as a psychological gambit: For every day that I don't spend money, my target balance still declines by ₩14,000, meaning my margin above zero increases by the same. It makes me feel like I'm constantly getting paid.