A little off-topic, but we all know that software construction depends more on coffee than on editors or compilers.
When I buy a cup of coffee, it's usually the drip-brewed stuff from Peet's. And I've always wondered how much of a "convenience fee" I'm paying in the store beyond the cost of brewing that same cup (same beans, strength, etc.) myself.
So I finally got around to figuring it out.
Peet's (and most gourmet coffee sellers) recommend two tablespoons of beans per 6-oz. cup of coffee. This is far more than most folks use at home, but it's not because the vendors want to pad their bottom line; rather, a strong cup of coffee similar to what is brewed at the store requires it. The 6 oz. number comes from the peculiar markings on American coffee makers, which count a "cup of coffee" as being 6 oz. (most likely because it's the volume of those formal old-fashioned china coffee cups).
The arithmetic works out this way:
- I measured and weighed Peet's French Roast Whole Bean coffee, and determined that the beans weigh 0.325 oz. per fluid oz.
- So a pound of these beans, at $11.95, contains 49.2 fluid ounces (this is a volume measure of beans; there's no fluid involved yet).
- Since two tablespoons = one fluid ounce, a pound of French Roast is enough to make 49.2 "cups" of coffee.
- The "cups" of coffee are 6 fluid ounces each, so our pound of coffee makes 295 ounces of brewed coffee.
- Each ounce of brewed coffee costs 4.05 cents, not counting the cost of water, electricity, etc.
Peet's charges $1.75 for a 16-oz. coffee in the store, which I could have brewed for 64.8 cents. Note that the store markup is probably a lot more than the 270% here, since my calculation is based on my retail price for the roasted beans, which should be higher than the internal Peet's cost.
Starbucks? The numbers should be pretty close, since Starbucks asserts that 2 tablespoons of its beans weigh 10 grams (0.35 ounces, pretty close to the 0.325 that I measured for Peet's), and their French Roast is $10.45/lb. These numbers imply a cost 3.81 cents per brewed fluid ounce.