What is the Pour-Over Coffee Powder-to-Water Ratio? Why is it 1:15?

For beginners, one common question is: how much water should be used for a cup of coffee? Why does FrontStreet Coffee use a 1:15 coffee-to-water ratio?

When tasting a cup of coffee, we naturally want it to have sufficient coffee flavor and be pleasant to drink. Coffee that is too strong can be uncomfortable, while coffee that is too weak might as well be replaced with plain water. Therefore, the first reason for using an appropriate coffee-to-water ratio is to control the coffee's concentration.

Concentration refers to the percentage of substances dissolved in a liquid. For example, in a 200-gram coffee solution with a concentration of 1.3%, the coffee contains 2.6 grams of dissolved substances. These 2.6 grams of substances are exactly what we extract from the coffee grounds by pouring water over them. The amount of substances extracted from the coffee grounds is called the extraction rate. Generally, an extraction rate between 18-22% is considered ideal. Using the previous example, if we use 15 grams of coffee grounds and extract 2.6 grams of substances, the extraction rate would be 17.33%.

Pour-over coffee belongs to the drip coffee category, where water continuously flows through coffee grounds, and the coffee liquid drips into the lower pot. For the coffee liquid, the more water you pour, the lower the concentration becomes, because the efficiency of dissolving substances is much higher in the early stages than in later stages. For the coffee grounds, the more water you pour, the higher the extraction rate becomes, though the rate of increase slows down as extraction progresses. To achieve a balance between extraction rate and concentration, a scientific extraction ratio has been established.

Coffee-to-Water Ratio

First, let's understand two concepts in pour-over coffee:

Coffee-to-Water Ratio: The ratio of coffee grounds to water, directly indicating how much water is used to brew coffee. For example, 1:15 means using 15 parts water to brew 1 part coffee grounds.

Coffee Grounds Absorption Rate: Generally, the saturated water absorption of coffee grounds is about twice their own weight (there may be variations, but it's basically around 2 times). Therefore, the amount of coffee liquid we obtain will not equal the amount of water we use for brewing. Taking a 1:15 coffee-to-water ratio as an example, the coffee grounds will absorb 2 parts of water, leaving us with 13 parts of coffee liquid.

After understanding these two concepts, let's look at the SCA Golden Cup Extraction Chart. This chart combines the preferred flavor ranges of European and American coffee drinkers with the relationship between coffee concentration and extraction rate. It serves as an excellent reference model.

SCA Golden Cup Theory

The SCA Golden Cup extraction range—Extraction Rate: 18%-22%, Concentration: 1.15%-1.45%.

In Golden Cup theory, coffee within this range is called Golden Cup extraction (considered "delicious" by the Golden Cup system, though not necessarily matching everyone's sensory preferences).

From the Golden Cup extraction chart, we can determine the maximum and minimum coffee-to-water ratios: 1:20.9 (concentration 1.15%, extraction rate 22%) and 1:14.3 (concentration 1.45%, extraction rate 18%). We observe that the 1:17 ratio passes through the largest area of the Golden Cup range, making it the easiest to hit the Golden Cup zone, followed by 1:16 and 1:18 ratios. Conversely, a 1:15 ratio is quite difficult to achieve within the Golden Cup range.

Why Choose 1:15?

Therefore, based on the Golden Cup extraction chart, the ideal brewing coffee-to-water ratio is 1:16-18. The 1:15 ratio is not recommended. However, when we conduct practical experiments, we find that although increasing the ratio (1:18) might fall within the Golden Cup extraction range for both extraction rate and concentration, it's easy to extract unpleasant flavors (during this process, concentration is easily maintained, but extraction rate is difficult to ensure). Therefore, the actual production ratio is correspondingly reduced, adopting a 1:15 coffee-to-water ratio.

FrontStreet Coffee has conducted multiple brewing experiments with light roast coffee and found that a 1:15 ratio typically yields a concentration between 1.35-1.42%, corresponding to an extraction rate of 17.79%-18.73%. Although this barely meets the Golden Cup standards, sensory testing revealed that the flavors were very appropriate, without the sharp acidity or astringency associated with under-extraction. This ratio is suitable for most coffee beans and represents a conservative, stable coffee-to-water ratio compared to larger ratios that more easily lead to over-extraction or bitterness.

Although 1.35%-1.42% is considered high concentration in Golden Cup extraction, we should remember that the concentration range provided by SCA references the tastes of American and European consumers. It doesn't represent the concentration preferences of people worldwide.

Is the Golden Cup Theory Incorrect?

Actually, it's not incorrect. Besides the coffee-to-water ratio, many other factors affect coffee extraction. For example, the cupping ratio we use is 18.18% (11g coffee, 200g water), which is actually the ratio most easily achieved within the Golden Cup range used by SCAA (the predecessor of SCA). However, this premise applies to immersion extraction.

Pour-over coffee, however, belongs to drip extraction, where water flow agitates the coffee grounds, thereby increasing extraction efficiency, which is why reducing the coffee-to-water ratio is also justified.

Does the Final Segment Necessarily Mean Bitterness?

A couple of days ago, some customers came to the shop for pour-over coffee. As the brewing entered the final stage, one friend suddenly started urging to quickly remove the filter cone to stop the flow, claiming this would avoid negative flavors from the final segment. FrontStreet Coffee has conducted comparison experiments following the normal 1:15 coffee-to-water ratio. By tasting the stopped flow from the final segment, we found no bitter or astringent flavors or other negative tastes. Blindly relying on "stopping the flow" actually loses some flavor compounds, resulting in coffee without aftertaste.

Usually, if the coffee brewed following the original framework still tastes off, either it's a problem with the coffee beans or there's a deviation in extraction parameters. Many high-quality coffee beans from renowned regions are of top grade locally and don't easily develop negative flavors, thus requiring no flow-stopping measures.

The reason champion competitors can "effortlessly" stop the flow is because they have accumulated countless brewing experiences with the same bean, allowing them to apply this technique so skillfully in competitions. For ordinary people like us, stopping the flow is mainly a rescue method. The action of removing the filter cone before the coffee liquid has finished flowing actually introduces uncertainties. One brew might taste good, but the next might not replicate the same flavor.

Important Notice :

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