Mystery

Question

From Mike

Dear Dr. Brew,
The one nagging question that no one has ever definitively answered: why a "cup" of coffee is 5 ounces.

My theory has been that's what grandma's china tea cups hold.

Is there another answer?

Thanks,

Mike

Answer

Serving size has always been a marketing mystery to me as well. As I learned to cook, a cup by volume was 8 fluid ounces. It's likely a cup at home held 8 ounces and was filled with 6 ounces for room to add cream and sugar. During my 30 plus years involved with beverage equipment and preparation I have heard the serving size/volume at both 5 and 6 ounces (never 8). My educated guess is that the number comes from a division of the final liquid yield of beverage.

As an example: If 68 ounces of water were dispensed over 4 ounces of ground coffee, the finished yield of brewed beverage (one ounce of coffee absorbs approximately two ounces of water) would be approximately 60 ounces. This is easily divided as 5 -12 ounce servings, 6 -10 ounce servings, 10 - 6 ounce servings, or 12 - 5 ounce servings to determine a cost per serving.

And Grandmother's tea cup started it all.

Happy Brewing,

Dr. Brew