Coffee is one of the few beverages that delicately straddle the line between simplicity and complexity.
Granted, anyone can make coffee. However, a blissful mug of coffee brings together a masterly of multiple factors, including finding the perfect coffee-to-water ratio. Because life is too short for bad coffee, here is your complete guide to the perfect coffee to water ratio.
This guide is a gradual introduction to the “brew ratio” concept, and it goes from the simple ratio numbers, to more complex tweaking techniques for the filter coffee enthusiasts.
If you only want to know how much coffee and how much water to use, you can stop there. But if you want to understand how can you change the brew ratio and other variables such as grind size, or brew temperature for better coffee, you can find that here as well. Just a longer read.
Definition: What Is Coffee to Water Ratio?
A coffee-to-water ratio, or brew ratio, refers to the amount of ground coffee used per unit of water. The coffee to water ratio determines a measurement that will ensure the best taste and flavor. It focuses on the taste of coffee, rather than economics, beverage strength, or concentration.
The ratio can be adjusted by multiplying with the same factor both, the water and the ground coffee. The ratio is a weight-based formula that you adjust for brewing any amount, be it one mug or an entire pot.
When brewing smaller amounts of filter coffee, the ratio might need to be adjusted, we’ll talk about it later in the article.
This ratio, ultimately, determines how much coffee and how much water you should use when brewing a pot. It is calculated for a certain set of brewing variables, and it’s often called the golden ratio.
Importance of Coffee to Water Ratio for Drip Coffee
The premise of a coffee-to-water brewing ratio is central to good coffee. We briefly mentioned this, but let’s get a bit deeper into the subject.
The third wave coffee movement changed the way we look at coffee and turned our daily cup from a commodity, to a luxury. This new perspective emphasized flavor, taste, and uniqueness over price, or convenience. This is how coffee to water ratio got the attention of professionals and home baristas alike.
Typically, the more coffee you use in a brew, the stronger the drink becomes. However, this says nothing for flavor. Overly strong coffee is not palatable. Drip coffee is not like espresso. If you brew it too strong it will taste bitter and tannic. And the brew ratio for espresso is totally different than drip, we talk about that more in our post here: Drip Coffee vs Espresso.
The proper coffee-to-water ratio will ensure you are brewing to the perfect strength and concentration.
Why Do We Need Precision?
Too little grounds, and you have a weak beverage; too much grounds, and you might end up with a bitter and tannic concoction. The brewing process is calculated so that extracts the right amount of soluble solids from the beans.
The beauty of coffee brewing is that the bitter unwanted compounds in coffee are harder to extract than the good stuff.
When we start brewing, there is a point in the process, when we extracted all of the caffeine, chlorogenic acid, and other phytochemicals and antioxidants that make coffee the amazing beverage that is. Go beyond this point and you extract bitter stuff. Stop to early in the process, and you won’t extract enogh of the good stuff.
Personal preference plays a role, obviously, and there are people who like a stronger cup, and over-extracted coffee is how they like it. Nothing wrong with that, to each their own.
However, coffee brewing is a precise, repetitive process, that has even a mathematical model. Applying the mathematical model allows us to brew precisely, and get a consistent flavor all the time.
So What Is The Coffee Golden Ratio?
While there is an artistic mastery to any well-brewed cup of coffee, well-balanced coffee brews consistently oscillate around a specific ratio. This takes out much of the guesswork by providing a benchmark dubbed the coffee golden ratio.
You would think that the Golden Ratio is a rigorous and precise set of numbers. You’d be wrong if you thought of that. Coffee taste is subjective. The best example is the statistical preference of coffee lovers in various countries. In Northern European countries the preferred brew ratio is 1:16. The resto of the Europe like coffee a bit less stronger, so they use a 1:17 brew ratio. North America like coffee on the weaker side, the most used ratio is 1:18.
These are just statistics, and recommendations based on these statistics. The coffee cup size and the serving also differ between these countries. Often the concentration is compensated by serving size.
The golden ratio for drip coffee is 1:15 to 1:18. This means for every 1 gram of coffee, we use 18 grams of water. For a stronger mug of coffee, use the 1:15 ratio;
What that does mean when brewing a pot of coffee? 1 gram of water is 1 milliliter, (density of water). What does that mean when you are brewing a coffee pot? Let’s take Oxo Brew 9 Cup coffee maker. The water tank holds 45 ounces of water, which translates into 1300 milliliters, (1300 grams). For a North American cup of coffee, you would have to use 72 grams of ground coffee. That is the ratio Oxo recommends, as a matter of fact.
If you want to measure that volumetrically, you can approximate 1 level tablespoon of coffee to about 5 grams. But this is just that, a rough approximation. Firstly, a level tablespoon is never filled that same, and secondly, coffee has different density, depending on coffee type and roast. So for brewing the full 9 cups, you would have to use about 14 to 15 tablespoons of ground coffee. (Note that there is an entire confusion about the 9 cups, which are coffee serving cups, not US cups. But this is a discussion for another article.)
To make things even more complicated, the ratio changes when you are brewing less coffee. Because the coffee bed is less deep, hot water tends to pass faster through the grounds. This means that if you brew a half a pot you should compensate by adding one or two extra tablespoons of coffee. Some machines, (like the Oxo Brew), have an option to brew less than pot. When you choose that option the machine extends the brew time so it compensates for the shallower coffee bed.
There are other ways to tweak the brew, when you don’t make an entire pot, and we’ll touch them in the next section, where we talk about other variables that affect brew ratio.
Brew Variables that Affect Brew Ratio
The golden brew ratio is calculated in relationship with other brew variables. And it is in a tight relationship with some of these variables.
Brew ratio influences the strength of your coffee, as we will see the preferred brew ratio varies geographically. So tweaking brew ratio is a way to play with the strength of your coffee. But for extreme adjustments, other variables might be a better option.
The most important variables that determine the brew ratio are:
- Grind size
- Water temperature, (brew temperature)
- Roast level
There are other variables that play a role, but is not as important as these three. Some of the other variables are: filter type, (paper filter vs permanent filter), water quality, (hardness), coffee type and origin, and brew time. However, when preparing drip coffee, brew time is determined by the grind size, and the filter type.
Out of the three major factors, only roast level is truly a variable. Grind size and water temperature should be constant, as recommended by the recipe. The recipe can be the recommended one from the coffee maker manufacturer, a famous barista recipe, or the generic SCA recommended ones: medium grind size, 200°F brew temperature, and 55g/L as the recommended coffee-to-water.
SCA doesn’t recommend a grind size, because it’s hard to measure particle size. They instead recommend total brew time 4 to 6 minutes for a medium grind.
But let’s take a closer look and see how the three major variables affect your coffee, and might require you to adjust your brew ratio.
If the coffee is too coarse, water can run through the grounds too quickly. If you need to use coarser grounds, (not sure why would you need it, but experimenting is a good reason), you can use more coffee grounds.
On the other hand, if the grind size is too fine, water will pool in the coffee bed, and extend the extraction time. This effect will be compounded with the higher extraction yield associated with finer grinds.
As a starting point, the pre-ground coffee is a perfect start, if you need a comparison term.
The recommended water temperature for brewing drip coffee is 200°F ± 5°. Hot water speeds up the extraction. The cooler the brew temperature the slower the extraction.
If you can control the water temperature, (you can with pour-over, and high end auto drip coffee makers), you can adjust the brew temperature to compensate for a lower brew ratio. If you own a variable temperature kettle and a manual dripper, you can tweak your cup of coffee to perfection.
The darker the roast, the more soluble the beans are. Light roasted coffees might need a higher brew temperature. Don’t get tempted to increase the brew ratio, although is the simpler route. You will get better tasting cup if you tweak the temperature.
Conversely, you can lower the brew temperature for very dark roasted coffee beans.
The other variables play a less important role in choosing how much coffee and how much water to use. If you skipped all together the rest of the list you wouldn’t lose much. However, understanding how these can affect your brew, will only deepen your understanding of the extraction process, and how different brewing methods and factors affect your cup.
The mineral composition of water affects the extraction yield. Distilled, or demineralized water will extract less compounds from the beans, whereas hard water will impart a bad taste to your final cup. According to SCAA, the perfect water should have TDS of 150 mg/L, with an acceptable range of 75 – 250 mg/L.
The Origin and Varietal of the Coffee Beans
The type of coffee plays an important role. Beans have different densities, and different composition. They behave differently when brewed, and they have different solubility. You might need a little less coffee when preparing Brazilian beans, compared to African ones. Brazil coffees have a lower density, in general. This makes them more soluble.
Take this with a grain of salt, and a lot of your own experimentation. Roasting is a more important factor than origin, and masterful roasting can render origin and varietal differences irrelevant.
The filter type important, especially when we talk about very specific brew methods. Many pour-over methods have designed their own coffee filters, which have a specific flow rate. The flow rate is calculated to provide a certain extraction, which in turn delivers a specific flavor. This is why the recipe is important.
For instance, the Chemex pour over uses a very thick filter that doesn’t allow fines to pass, but this slows down the flow a bit. The recipe reflects that in the grind size. But this can be also controlled by tweaking the amount of coffee used.
In drip coffee, the grind size will affect the brew time. There are other ways to control the extraction time, if you are particular about a certain grind size. One way as we mentioned is the coffee filter type. A permanent filter will allow more fines and oils in your cup, but will be very sensitive to grind size.
Another way to control the brew time is with the hole in your filter cone. Some of them come with three holes, and you can block two of them with rubber stoppers, in order to slow down the flow. This means you don’t need to absolutely rely on grind size and brew ratio to get the perfect 5 minutes brew time.
I’d like to end this section by mentioning that automatic drip coffee makers are calibrated to a single grind size, temperature, and brew ratio. With a coffee machine, you can only make minimal changes to the recipe. Recipe tweaking works better with pour over coffee devices.
How to Measure Water and Coffee Beans
Let’s get to some more practical advice now. The best way to measure your ingredients is on a scale. That is the most precise method. However, this might not be very convenient when done on a regular basis, and close approximations are good too.
Water measuring is relatively simple. You just fill the water tank to the line. The manual should tell you how much water it takes.
For coffee, as a rough estimate, one level tablespoon of ground coffee is about 5 grams. You will then calculate how much you need for your water tank.
Let’s take as an example the Ninja CE251 Programmable Brewer. The water reservoir of the CE251 holds 60 fluid ounces, which is 1.7 liter. So we will need 1700 ml of water and 94 grams of coffee grounds for a 1:18 brew ratio. The 94 grams of coffee are going to be roughly 19 level tablespoons of grounds.
I strongly recommend using a digital scale for the coffee grounds. Measuring on a scale is much easier and gives you precise amounts and measurements.
By following the recommended ratio of 1:15 to 1:18, you can ensure you get at least a decent cup. But to me, coffee should be perfect, so try play with those numbers.
I hope this article helped you understand that coffee to water ratio is a dynamic variable, that is influenced by the other brewing factors. This should hopefully help you make delicious coffee, to your taste. Experiment and find what works best for you. Never stop tweaking your cup, until you are happy with it.
If the heavy technical information is too much, just follow the values in the table and you won’t be wrong. Come back to this article when you are ready to experiment.