September 14, 2009

Washing Dishes is Cheaper than Buying Paper Plates

[Update comment. 3/1/16 -   This article is pretty old now.   In hindsight, and as pointed out by comments, the math below is full of holes.  - Jim ]

In Trent's weekly reader mailbag over at The Simple Dollar he had a reader say that they thought that the cost of washing dishes was probably equivalent to the cost of buying paper plates. I doubted that so I figured I'd run the numbers and figure it out.

So, which is cheaper, washing plates or buying paper plates?

Cost to Wash plates

Based on the energy guide for a typical dishwasher the cost of running a new energy efficient dishwasher is about $35 a year to run 4 loads a week. Thats just $0.175 per load. An older dishwasher could use twice as much or more electricity so that might run $0.35 or more per load. The water used is only a few gallons and the cost of that is a fraction of a cent. So for estimating purposes we can figure that it costs $0.35 or less to run a load of dishes. I am not sure how many plates you can fit in a dishwasher. But I'd assume that I could probably get about 20 into our dishwasher. So if you wash 20 plates for a cost of $0.35 then that comes out to a cost of 1.75¢ per plate to wash. You also have to buy detergent. A $3 box of Cascade has 20 oz. and should handle 20 or more loads (I'm not sure how many loads/box but I'm guessing). So that amounts to another $0.15 per load or 0.75¢ per plate

Cost of paper plates

The very cheapest paper plate that I see for sale at Safeway or in bulk at Costco is 3¢ per plate.

So in summary:

Cost to wash a plate = 1.75¢ electricity + 0.75¢ = 2.5¢
Cost to buy paper plate = 3¢

Winner: washing plates

[edit : I forgot the cost of dishwasher soap when I first wrote the post, so I added that after the fact]

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