Pour-Over Coffee Grind Size Standards and Adjustment Parameters

Whether it's on online platforms like Taobao or WeChat, or in our physical stores, many coffee enthusiasts frequently ask about coffee grind size. FrontStreet Coffee's response is often just six words—"fine as granulated sugar."

How Fine is Granulated Sugar?

For some coffee beginners, this might be a bit too technical, as we're dealing with millimeter-level precision, which is truly difficult to grasp. So exactly how fine is granulated sugar?

According to the GB 317-2006 technical requirements for white sugar, white sugar is classified into four levels: refined, premium, first grade, and second grade. Different grades of sugar vary in purity and particle size precision. Sugar particle values are also categorized as coarse grain (0.800-2.50mm), large grain (0.630-1.60mm), medium grain (0.450-1.25mm), and fine grain (0.280-0.800mm), with uniform crystals within the specified ranges accounting for at least 80%.

Typically, such comparisons require visual and tactile discrimination to distinguish their differences. Unless one is highly experienced, it's difficult to achieve precision, making it particularly unfriendly for beginners. Additionally, after coffee beans are ground, the coffee particles have irregular shapes compared to sugar crystals, making them even more challenging to assess precisely, both visually and tactilely.

Why is Grind Size Important?

To experience the impact of grind size most intuitively, coffee enthusiasts can brew whole roasted coffee beans, sugar-sized coffee grounds, and flour-like fine coffee powder using the same water temperature, same coffee-to-water ratio, and same brewing time, then taste and compare the extracted coffee liquids.

As we commonly understand, with a given amount of coffee beans, the larger the surface area of the extracted material, the more substances will be released within the same time. However, not all substances released by coffee produce good flavors, so we need to find an appropriate grind size to extract the desirable flavor compounds from the coffee.

How to Choose Grind Size?

If you have multiple coffee brewing devices at home, you'll notice that each brewing method corresponds to different particle sizes. For example, espresso, known for its intense flavor, is made using semi-automatic espresso machines, and the coffee particles used for this Italian-style coffee are around 0.2-0.3mm. Meanwhile, pour-over coffee, which we most commonly encounter and discuss, ideally has coffee particles between 0.6-0.8mm.

However, the particle sizes mentioned here are all within 1 millimeter. I'm afraid some naive enthusiasts might immediately look for measuring tools to measure them. The question is: do you have a measuring tool that can measure 0.1 millimeters? Even if you do, how would you measure? You'd go cross-eyed trying to measure them all!

At this point, FrontStreet Coffee would like to introduce a tool, something often mentioned when discussing grind size—the Chinese standard #20 sieve (0.85 millimeters). Regardless of the price point of the grinder, the resulting coffee grounds will always have both coarse and fine particles. Therefore, we want the majority of coffee grounds to be within the 0.6-0.8 millimeter range. FrontStreet Coffee uses an 80% pass rate through a 0.85mm standard sieve as the grind size standard for light to medium roasted coffee beans.

However, besides judging coffee grind size through data, we can also determine if the grind size is appropriate based on the coffee brewing process. Brewing time serves as a reference—FrontStreet Coffee's standard brewing parameters specify that a pour-over coffee should extract within 1 minute 50 seconds to 2 minutes 10 seconds. If the grind is too fine, extraction time will extend; if the grind is too coarse, extraction time will shorten.

Alternatively, you can observe the settling speed of the coffee grounds during brewing. Generally, the coffee bed should settle slowly and evenly. If it settles too quickly, the grind might be too coarse. If the settling speed becomes progressively slower or even gets blocked, it might indicate that the grind is too fine or there are too many fine particles, creating a muddy consistency at the bottom of the coffee bed.

Case Study: Honduras Sherry Coffee

Next, FrontStreet Coffee will use Honduras Sherry as an example, choosing two different grind sizes for comparison. First, as usual, FrontStreet Coffee will introduce this coffee bean.

Honduras Sherry

Region: Masaguara region, Honduras
Estate: Moca estate
Altitude: 1500-1700m
Varieties: Caturra, Catuai, Pacas
Processing: Fine washed whiskey barrel fermentation

Honduras is located in northern Central America, bordered by the Caribbean Sea to the north and the Gulf of Fonseca to the south, sharing borders with Nicaragua and El Salvador to the east and south, and Guatemala to the west, consisting mostly of mountains and plateaus.

At the Moca Coffee Estate, because the growing area is mountainous, people hand-pick coffee beans and then carefully process them to produce higher quality coffee beans. Honduras harvests three million bags of coffee annually, providing abundant, high-quality coffee to the world, and has now become one of the top ten coffee exporting countries.

This coffee bean contains three coffee varieties: Caturra, Catuai, and Pacas.

Caturra

Caturra is a natural variant of Bourbon, discovered in Brazil in 1937. Caturra plants are smaller than Bourbon plants. Although inheriting Bourbon lineage, Caturra has relatively weak disease resistance but higher yields than Bourbon. Although Caturra was discovered in Brazil, this variety is not suitable for growth in Brazil but is widely popular in Central and South America, such as Colombia and Costa Rica.

Catuai

Catuai is a coffee variety artificially hybridized from Caturra and Mundo Novo. Catuai has good resistance to natural disasters, especially wind and rain. Catuai plants are shorter compared to other coffee varieties, and Catuai fruits are not easy to harvest. Catuai variety fruits come in both red and yellow.

Pacas

Pacas is a natural variant of Bourbon, resulting from a single gene mutation. This variety was discovered in 1949 on a farm belonging to the Pacas family in the Santa Ana region of El Salvador. In 1974, the Honduran Coffee Institute introduced this variety and cultivated it in Honduras.

FrontStreet Coffee's Honduras Sherry uses fine washed whiskey sherry barrel fermentation processing. This method involves first performing fine washing of freshly harvested coffee cherries, then placing them in whiskey oak barrels that have matured sherry wine for low-temperature fermentation for 30-40 days (at approximately 15-20°C), followed by shade drying.

Okay, now let's explore how grind size affects this Sherry coffee.

First, we selected two grind settings: Group A at BG #8s and Group B at BG #3s. Then we conducted cupping procedures and concentration tests.

The experimental results showed that Group A had a concentration value of 0.78%, while Group B had a concentration value of 1.17%.

More extracted compounds are not necessarily better. Too fine a grind will extract more large molecular substances from coffee that produce bitterness. An appropriate grind size can avoid under-extraction that leads to incomplete flavors and weak taste, while also reducing the risk of over-extraction that causes coffee to taste bitter, strong, and astringent.

For professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat official account: cafe_style). For more specialty coffee beans, please add FrontStreet Coffee on WeChat: kaixinguoguo0925

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