What is the Standard Grind Size for Pour-Over Coffee? How to Accurately Find the Right Grind Size?

The reason most people struggle to make good coffee is primarily not selecting the right coffee grind size. This is something FrontStreet Coffee has consistently emphasized, because in many cases, this is simply the truth.

Extraction rate and concentration are the two key factors that determine whether a pour-over coffee tastes good. In the coffee-making process, four important factors can control the extraction rate and concentration: grind size, ratio, time, and water temperature. The parameters of each factor affect the coffee's extraction rate, so to make a delicious cup of coffee, we need to use the appropriate extraction parameters.

Among these four factors, only the coffee grind size is in an invisible state, while the parameters of the other three can be directly observed by us. Therefore, when we use the same materials (beans and water), the same brewing method, and seemingly the same parameters to brew a pot of coffee but it doesn't taste as good as what's made in the shop, don't doubt it—the problem is most likely with the coffee grind size (less likely that it wasn't brewed properly).

Because the coarseness of coffee grounds is not intuitive, most of the time we can only use visual and tactile judgments, then compare them to substances like fine sugar, coarse sugar, etc. However, this description is not reliable, mainly because the range is too broad—everyone's definition of sugar particle size is different, and the coffee ground size we see from appearance is merely superficial. So, how can we accurately find the right coffee grind? You might want to refer to the three methods shared by FrontStreet Coffee below~

Sieve Measurement Method

"A certain percentage passing through a #20 sieve" is a parameter that FrontStreet Coffee often shares in articles. This value is obtained by using a #20 sieve to measure coffee grounds. Compared to other methods, using a sieve can provide a more objective standard, so there will be less error when everyone compares. Because everyone uses different machines and beans, specific grind sizes cannot be communicated through machine models and settings. Even with the same machine at the same setting, differences in burr wear can result in variations in coffee ground coarseness. The use of a #20 sieve can provide relatively reliable data, allowing everyone to adjust to a similar coffee grind size through #20 sieve measurements, even when using different equipment and materials.

The #20 sieve has an aperture of 0.85 millimeters, and its box-like design consists of upper and lower layers. The operation is simple: we only need to put a certain amount of coffee grounds into the sieve and shake it! Stop when no more coffee grounds pass through the sieve. Then we just need to measure the weight of the coffee grounds, and we can get an intuitive result. For example, if FrontStreet Coffee puts in 10g of coffee grounds, and the amount that passes through the sieve is 7g, then the passing rate of this coffee grind is 70%. If others want to use the same grind size as you, they only need to adjust the grind until the passing rate reaches 70%. This applies to any machine and any beans.

Here are the grind sizes that FrontStreet Coffee uses when brewing pour-over coffee for your reference: hot brew coffee has a grind with 80% passing rate through a #20 sieve, while cold brew coffee has a grind with 85% passing rate. However, the sieve method also has limitations—it can only distinguish particles larger/smaller than 0.85mm. In the article "How Much Does Coffee Bean Grinding Affect Extraction?", FrontStreet Coffee emphasized that due to grinding characteristics, coffee grounds come in varying sizes. Even high-quality grinders cannot achieve complete uniformity; they can only control the coarseness of most coffee grounds within a certain range. (Below is a sample of coffee grounds ground by an Ek43, which FrontStreet Coffee separated into large, medium, and small particles using sieves)

Therefore, when we use a lower-quality grinder or when the burrs are dull, the resulting coffee grounds will be very uneven. Even if our values match others' passing rates, there will still be significant differences in taste. In such cases, FrontStreet Coffee would recommend using two other methods to determine the appropriate coffee grind size.

Water Flow Speed and Extraction Time

The coarseness and uniformity of coffee grounds affect the water flow speed during brewing. Coarser coffee grounds result in faster water flow, while finer coffee grounds result in slower water flow. Water flow speed affects the contact time between water and grounds—longer extraction time leads to higher extraction rate, and vice versa. Therefore, with all other parameters fixed, we can determine the coarseness of coffee grounds by observing the water flow speed.

Take FrontStreet Coffee as an example: when brewing a pot of light roast coffee, we use 15g of coffee grounds, water temperature of 92°C, ratio of 1:15, and extraction time between 2 to 2.5 minutes. If the final brewed coffee falls outside this range, we need to make corresponding adjustments to the grind. Since all parameters are fixed, only the grind can change the extraction time. If the water flows too fast, adjust to a finer grind; if the water flows too slow, adjust to a coarser grind—it's as simple as that~

Of course, relying solely on extraction time to judge the quality of a cup of coffee is not entirely advisable, so we need to combine it with a third factor for evaluation: taste.

Taste

As FrontStreet Coffee mentioned at the beginning, extraction rate is crucial for a cup of coffee because it represents how many components from the coffee have been dissolved. These components are the main contributors to coffee flavor. When too much or too little is dissolved, they diminish the positive experience of a coffee. Therefore, by tasting the coffee's performance, we can determine whether the coffee grind needs to be adjusted finer.

FrontStreet Coffee previously explained the specific principles in detail in the article "Coffee Tastes Bad? Teach You How to Distinguish Between Over-Extraction and Under-Extraction," so here's a brief explanation of how to determine if coffee is poorly extracted based on its performance. When too few substances are dissolved from the coffee, this is what we call under-extraction. Due to the lack of sufficient sweet and bitter substances to balance the acidity, the coffee will have a relatively sharp acidic taste, not only that, but the coffee's body will be very thin due to insufficient substances, with basically no aftertaste. If we taste this condition in our coffee, then without changing other parameters, we need to adjust to a finer grind to increase the coffee's extraction rate.

And if the coffee tastes very full but has明显的杂、苦味道，那很有可能就是咖啡萃取过度。像这种情况如果其它参数保持不变，那么我们就可以通过调粗研磨来降低咖啡的萃取率，以此让咖啡的苦、杂味道无法过多溶解。以上这些技巧都是建立在磨豆机的质量相对稳定的情况下，如果磨豆机的质量太差，亦或者是刀盘太钝，磨出来的细粉非常非常多，使咖啡液在萃取的过程中出现了严重堵塞的现象，那最好还是将磨豆机进行更换最为妥当。当然啦，我们也可以通过调整其它的参数来达到合理萃取的目的。但是这对于萃取理论的理解要更深一些，如何选择如何调整，就看大家自己啦~

And if the coffee tastes very full but has noticeable astringent and bitter flavors, it's likely that the coffee is over-extracted. In this situation, if other parameters remain unchanged, we can adjust to a coarser grind to reduce the coffee's extraction rate, thereby preventing excessive dissolution of bitter and astringent flavors. All these techniques are based on the premise that the grinder's quality is relatively stable. If the grinder's quality is too poor, or if the burrs are too dull, producing excessive fine grounds that cause severe blockage during extraction, it would be best to replace the grinder. Of course, we can also achieve proper extraction by adjusting other parameters. However, this requires a deeper understanding of extraction theory—how to choose and how to adjust is up to you~

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473