Coffee cup measure experiment


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Jan 27, 2022
Upstate New York
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I had some time on my hands and a good digital scale. So I thought I would do a test.

I have a collection of carafes from various drip coffee machines that long ago died on me. Seven carafes actually. All of them have graduation marks on the side to indicate the number of cups. They all claimed to be 10 or 12 cup carafes.

So I would measure out five cups per the carafe markings - and then weigh it on my scale. I did many measurements many times.

My results: the graduations on the carafe vary from carafe to carafe. From 24 grams to 27.5 grams, or 4.8 grams to 5.5 grams per cup. None were up to 6 grams (the standard coffee cup measure).

I am talking beyond eyeball inaccuracy. I would repeat the measurements on a given carafe many times and take an average. I'm a nerd so did a spreadsheet and some elementary statistical analysis.

So what is my conclusion: the markings on the side of the carafe are meaningless. They are not a real cup (8 oz.). They are not a coffee cup (6 oz.) and they are not consistent from coffee machine to coffee machine.

Always be suspicious when the result of your experiment confirm your preconceived notions. But yea, I kind of knew going in they were not going to be a reliable of a cup.

Some day soon I will measure tablespoons of grounds, and weigh them, to see how variable that measurement is. I will let you know.

Lesson - use a digital scale, measure your ratio of grams of water to grams of coffee. That is the only measurement you can trust. I use a ratio of between 16 to almost 18. My sweet spot is 17 for a medium light roast coffee.
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BINGO... since you appear to like to nerd out like myself, take a light / medium and dark roast. Get 3 identical jars and fill and pack each one with coffee. You will be shocked to see how much more dense less roasted coffee is... proves the point to brew great coffee measuring weight is key!
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You are right, and I stumbled on this the other way. I grind 50g of coffee typically, for my pour over. I was surprised to find how 50 grams of this coffee takes up more room than 50 grams of that coffee.. Coffee density is an issue. The same number of beans in one type of coffee weighs more than in another type of coffee.
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