How To Slash the Amount of Money You Spend On Laundry Detergent
Look at the little plastic measuring cup they pack in the box.
Seriously, that’s it. That’s all there is to it. But most people, it turns out, never do that; they just fill the plastic cup up to the line near the top.
If you take the time to look at the cup, though, you’ll find out that line is waaaaaay more detergent than you need for a typical load of laundry. There are other lines farther down the cup, too. On the cup that came with my last box of Tide, for example, there are three lines: one near the top (labeled with a prominent number "2"), one about halfway down the cup (labeled with a less prominent number "1"), and one below that at about 3/8ths of the way up the cup, carrying no label at all.
When you read the instructions on the box, you discover that the lowest line is all you need for your typical washing machine load — line #1 (half the cup) is recommended for "large loads", and line #2 (nearly a full cup, the one people instinctively use) is for "heavily soiled large loads".
If you start using the lowest line, you’ll see absolutely no difference in the quality of the wash your clothes get (unless you use an abnormally large washer), and you will double the number of washes you get out of a single box of detergent. Which means that you’re cutting the amount you spend on detergent in half.
Now you know why they give you a plastic measuring cup, rather than just telling you how much detergent to measure out — if you were using your own measuring cup, you’d actually measure the detergent. By using their measuring cup, they can take advantage of your inattention to get you to use more than you actually need.
And the landfills fill up with used plastic measuring cups, too! Joy.
(Thanks to Raymond Chen for bringing this to my attention in the first place.)