How much does a minute cost?

How can I evaluate the cost of a minute?

It's tempting to think of time in terms of how much money I could make if I were working with that time. I could divide out my salary over the course of my year and then know how much my time is worth if I spend it "productively." But that's not really accurate, in my opinion. If I free up a minute, I'm not really using that minute to earn a paycheck. What am I really doing?

I'm reducing the cost of the tasks I'm optimizing. Rather than think about how my income should change if I free up minutes, I should consider that I am paying money to keep myself alive. This amount is somewhat independent from income. I'm not saying that every minute I free up is now billable per my regular pay; I'm saying that each minute I'm alive costs me X dollars and that the task of, say, showering, now costs me less.

So, if I go to Tilex or some other spray to prevent soap scum and mildew, rather than use a squeegie and a towel, I need to quantify the costs of the task for either alternative. Time costs money. So does Tilex. So does infrequent squeegie replacement and regular towel-washing. Let's assume that the squeegie is replaced twice a year and that washing the towel costs nothing. How much does Tilex cost?

$7.50.

Tomorrow I'll try to figure out how much a minute costs, which should be useful for all kinds of things in the future.