Brewing Coffee – Grinds to Water Ratio
One cup is 8 ounces, ½ pint or 236.6 ml
Two cups, 16 ounces equals a pint
Four cups, 32 ounces is a quart or .946 L
Eight cups, 64 ounces is two quarts
Sixteen cups is 128 ounces or 4 quarts or 1 gal
What is this, the appendix of The Joy of Cooking? And what does all this have to do with coffee?
Well it has to do with the fact that brewers are graduated for five ounce cups, and coffee shops sell 12, 16, and 20-ounce beverages.
It’s all about figuring out how much coffee grinds are appropriate and necessary for the proper strength of brewed coffee produced by your brewer. The amount of grind used for brewing is sometimes called the “drop.”
We in coffee labs, do cup testing of coffees for various purposes, always using consistent conditions, measurements and other norms. We test coffee at a strength we accept to be the industry standard for brewed strength. We use a quarter ounce of coffee grinds to five ounces of water. Five ounces has become the average cup-size marking on most home brewers sold today. .
Anyway, the so-called commercial “bottle-brewer” or “pour-over brewer” has a glass carafe that holds 64 ounces when just filled to the plastic rim about the neck. These brewers are now commonly referred to as 12-cup brewers because; not surprisingly they yield twelve 5-ounce cups of coffee. Four ounces of water will stay saturated in the grinds remaining in the filter basket. A 12-cup brewer rarely produces 12 servings.
Pardon my rambling but we have some diverse issues here. A “cup” of coffee can no longer be expected to be eight ounces and it could be five ounces, and the average eight ounce ceramic cup at home usually holds seven ounces.
Regardless the cups size, one needs to measure the amount of water being supplied to a brewer to determine the proper amount of grinds if you wish to brew a good strong cup of coffee. During my childhood, my dad sometimes complained that the restaurant coffee tasted like “dishwater,” not that he ever tasted dishwater mind you. But you get the idea.
The Specialty Coffee Association of America currently has a certification program called the Gold Cup Standard. This is an award for recognition of a café that properly brews a good strong cup of coffee that is not over extracted or objectionable in any number of other ways. Since the nineteen forties the Pan-American Coffee Bureau, The Coffee Brewing Institute and the Coffee Development Group have all wrestled with the dilemma of Dishwater Coffee.
To meet the criteria for this distinguished award, one has to meet standards for proper grind, proper grounds to water ratio, be able to consistently produce a beverage with 1.25% total soluble solids and an extraction value of approximately 20%.
With all this well in hand, one can still be stymied by the fact that some origins have different extraction values and that different degrees of roast will also have an effect on extract values. Issues such as water quality, water temperature and the total length of time for the filtration process (dwell time) will also affect the taste of your coffee. Not to mention that bad coffee can be brewed perfectly well and still taste like bad coffee.
As some coffees are naturally stronger than others. Colombian and Kenya have good reputations in this regard. Also heirloom varieties have long been known to produce stronger brews than most of the new hybrids, simply because they produce more soluble solids.
If you have a taste for the pungent – piquant and somewhat burnt-sugar flavor of dark roast coffees, you might think them stronger than medium roasted coffees. You would most likely be wrong. The so-called French Roast is really only stronger in burntness and bitterness, but weaker in Total Dissolved Solids (TDS) the actual coffee extract. Darker roasts are actually weaker in general because much of the flavor aromatics are vaporized and remanded to the chimney during the extended and more aggressive roasting process. By the way, dark roasts are not even stronger in caffeine either. Sorry about that.
I personally use a bit more dark roast coffee grinds in my brewer to make up for the lighter extract. One could also grind the beans a little bit finer to make it taste stronger, but that can increase bitterness by contributing to over extraction.
Now the important thing to remember after all this miscellaneous rambling is that a pound of coffee should produce between forty and sixty cups of good strong coffee regardless the brewer.
A 12-cup brewer with two and a half to three ounces of grinds, makes three respectable Venti’s.
Be picky about your source of beans; remember “garbage in, garbage out.”