Brewing the Perfect Cup of Coffee – Variables For Success

Jan 5, 2017

So you bought awesome, single-origin, specialty grade coffee. Now what?


If only brewing great coffee could be as simple as buying great coffee beans. In the wine industry, the wine maker has complete control over their product from start to finish. You know you’ll enjoy a wonderful glass of wine when you buy it from an excellent winemaker. Unlike the wine industry, coffee requires that customers use a bit of their own barista skills in order to brew their cup. This can be a great thing or an unfortunate thing depending on how you look at it. On one hand, errors in brewing can ruin the quality of coffee, producing a less than enjoyable cup – wasting the time and money that went into brewing it. On the other hand, if you are armed with the proper tools and information, you can tweak brewing recipes to highlight the best aspects of the coffee and tailor it exactly to your preferences. 

We’ve talked a little bit about the importance of proper extraction in the past, but we thought it would be a good idea to go into more detail about some coffee brewing variables to help you troubleshoot your brew and ensure that you’re getting the amazing cup of coffee you deserve. 


1. Water

Besides having high quality, freshly roasted coffee beans, the most important ingredient in a cup of coffee is the water. Just like a great meal starts with high quality ingredients, you’ll never be able to achieve a great tasting cup of coffee without good water.  A brewed cup of coffee is actually 98% water, so make sure that you are using water that you would want to drink! 

As a rule of thumb, the SCAA recommends water that is clean and clear, and free of odors and chlorine. We recommend using a water filter like a Brita or buying bottled spring water.

For a more in depth look at water and the best types to brew with, check out this article from Manual Coffee Brewing

2. Coffee Brewing Ratio

The brewing ratio is probably the variable most often ignored by novice coffee brewers. We cannot stress enough the importance of proper extraction in brewing coffee. Extraction is the science behind what turns coffee beans into the delicious beverage we know and love. The coffee brewing ratio is arguably the most important variable when thinking about coffee extraction, so if you want to troubleshoot your brew, this is a variable worth looking at. 

Most coffee professionals agree on a coffee to water ratio within the range of 1:15 to 1:18 (by weight!) 

While you can make slight adjustments to taste in your brewing ratio, it is best to try to stay within the above range. Why? Coffee is comprised of many different sugars, acids, and alkaloids. Some of those flavors are wonderful, while others aren’t so wonderful.

The goal with extraction is to try to get as many of the desirables as possible while leaving behind the flavors that aren’t as palatable.

If you go outside the given range of ratios, you run the risk of either extracting ALL the flavors (good and bad), or not extracting enough of the flavors (sacrificing sweetness and complexity).

*we cannot recommend enough that you use a scale to weigh out your coffee and water. Using a volumetric measurement will never give you a consistent cup as coffee beans vary in density and size, and will affect your overall extraction

3. Grind/Brewing Method

Adjusting your grind size can be the difference between a complex, nuanced cup of coffee and a bitter or underdeveloped cup of sadness. 

Simply put, a finer grind = more extraction while a coarser grind = less extraction (over the same amount of time).

The rate of extraction increases as surface area increases. The finer the grind, the more surface area of the coffee is exposed. Therefore, coffees with a finer grind extract flavors more rapidly and are better suited for quick brewing methods. If you are using an espresso machine or an Aeropress, you will need a finer grind. If the coffee grounds spend more time interacting with water, you want to slow the extraction process to avoid getting undesirable flavors. This is why a coarser grind is necessary for full immersion brewing methods like a French Press or Clever Dripper. 

If the contact time is too high or the grind is too fine, it will result in an over-extracted, bitter brew. If the grind is too coarse or the contact time is too short, the coffee will be weak and sour. 

*we always recommend grinding your coffee fresh with a burr grinder before brewing. If you don’t have a burr grinder, a blade grinder is fine. It will be difficult to retain consistency, but freshly ground is always best.


4. The Three Ts

The Three Ts of combustion are coincidentally the same Three Ts of coffee – time, temperature, and turbulence. We have them grouped together for the purpose of this guide, but keep in mind that each of the three variables are separate and need to be manipulated separately during your experimentation.


Time is an important element in coffee brewing, as the amount of time the water is contact with the coffee determines the amount of solubles extracted. We touched on this concept when we talked about grind size. While most brewing methods require a 4 minutes brew time, there are exceptions (espresso or Aeropress).It’s always a good idea to check and make sure what the proper brew time is for the device, grind, and water temperature you are using. 

Which brings us to:


As a general rule, your water temperature should be between 195 and 205 degrees Fahrenheit. (If you don’t have a kettle, you can also bring your water to a boil, remove it from the heat, and let it sit for a few moments before pouring it over your grounds.) That is the range where water-soluble flavor compounds most easily dissolve in water. If your water is too hot, you will scorch your beans, and if your water is too cool, you will under extract your brew. Again, there are some exceptions to this rule. Some recipes for the Aeropress require a water temperature of only 190 degrees Fahrenheit.

To make up for the lower water temperature, however, it is necessary to utilize:


Turbulence happens every time you brew coffee. It is created simply as water passes through and over the coffee grounds, allowing the particles in the coffee to separate and water to flow around and through the particles for proper extraction. Water that is poured too slowly over the grounds can create channels in the grounds that are not evenly wet and extracted. This is a common flaw in pour over brewing methods and is the reason for pre-wetting your grounds. 

Full immersion brewing methods and recipes that require a low water temperature need an extra push of turbulence in order to fully extract. About 30 seconds after pouring your water over the coffee, make sure to stir the grounds and ensure that they are all fully immersed in the water.

Unfortunately, there is no exact rule for how long or how vigorously you should stir your grounds. You’ll have to decide that through experimentation! 


Parting Thoughts

Ultimately, it is important to remember that a good cup of coffee is the result of a variety of elements that all work together. While you can change one variable to manipulate your brew, every variable is important and they work together to bring you a great cup of coffee.  If you are going to invest the time and energy in brewing a cup of coffee at home, you can’t skimp on one of these parameters.

It may be easy to forget, but brewing coffee is chemistry. And these variables are based on scientific research conducted by the SCAA and other foundations. Keeping them in mind is vital to the success of your perfect at-home brew. 

At the end of the day, remember this: we only want you to enjoy your coffee. And good beans deserve a good brew.

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