What grind size and brew time does a moka pot need?

Grind size decides whether extraction succeeds, and sieve pass-through rate describes it more precisely than words like caster sugar or flour. For a moka pot, the grind sits in the fine range, finer than pour-over and coarser than espresso, and the brew finishes in a few minutes once the water in the base heats and pressure pushes it up through the coffee bed.

The article sorts grind levels for pour-over, cold brew, ice drip, French press, Clever Cup, moka pot and espresso, with pass-through rate references for the No. 20 Chinese standard sieve. It also covers medium-light versus medium-dark roast pour-over, iced pour-over adjustments, and why finer cold brew grind does not improve the cup.

Grind size is one of the core parameters that determines whether coffee extraction succeeds or fails, but the coarseness of coffee grounds is hard to describe with intuitive numerical values, so sieve pass-through rate has become a more precise way to communicate. In this article, Front Street Coffee will systematically sort out the suitable grind levels for pour-over, cold brew (cold immersion and ice drip), French press, Clever Cup, moka pot, and espresso machine, and provide specific pass-through rate references for the No. 20 Chinese standard sieve. Whether you are a beginner just starting out or a veteran looking to calibrate your grind, you can find corresponding parameter suggestions here. The article also specifically explains the differences between medium-light and medium-dark roast pour-over, adjustment methods for iced pour-over, and why cold brew grinding is not better the finer it is, helping you avoid common pitfalls and brew a full-flavored cup of good coffee.

Not all the substances that can be dissolved from coffee beans are pleasant-tasting; some less appealing components are mixed in as well. To get a delicious cup of coffee, the key is to let the good flavors fully release while suppressing the extraction of undesirable substances as much as possible. To achieve this goal, you need reasonable extraction parameters to regulate the dissolution process, and grind size is one of the most important links in that chain. Many times when we cannot brew the ideal flavor, the problem often lies in choosing the wrong grind size—this principle applies to all coffee.

Recently, quite a few friends have come asking about grind size, with inquiries about cold brew, pour-over, moka pot, and various other methods. So today Front Street Coffee will talk about how coarse or fine the grind should be for different extraction methods. But before we dive in, there is one thing we need to clarify first…

Grind size does not have a clear numerical value to refer to like water temperature or water amount, so when discussing the coarseness of coffee grounds in daily conversation, people tend to use analogies such as "caster sugar" or "flour." But this approach has an obvious shortcoming: the naked eye simply cannot accurately judge which level the particles belong to, and can only make a rough estimate. As a result, everyone's idea of "caster sugar" is different, and even if all other conditions are identical, the brewed coffee can taste vastly different.

In addition, because everyone uses different brands and models of grinders, communicating grind size by grinder settings also does not work. In this situation, Front Street Coffee recommends using sieve pass-through rate for communication, and this article will also adopt this standard when sharing grind sizes.

The sieve mentioned here refers to the No. 20 Chinese standard sieve with an aperture of 0.85 millimeters. It was originally a tool for grading and testing granular materials, and it can also be used to calibrate coffee grind size.

The method is simple: pour the ground coffee into the sieve and shake it repeatedly until no more particles fall through, then weigh the fine powder that passed through and calculate the pass-through rate, which gives you a rough judgment of the grind coarseness.

Front Street Coffee gives an example: suppose you take 10 grams of coffee grounds, and the powder passing through the sieve weighs 7.1 grams, then the pass-through rate is 71% for the No. 20 sieve. The higher the pass-through rate, the finer the grind; conversely, the coarser it is.

Once you understand how the pass-through rate is calculated and what it means, you will be able to intuitively grasp just how coarse or fine the grind sizes shared by Front Street Coffee below really are.

I. Grind Size for Pour-Over Coffee

Let's start with pour-over. Pour-over is a drip extraction method, relying on manual pouring to quickly brew a cup of flavor-rich coffee. Because the overall extraction time is relatively short (brewing 15 grams of coffee takes about 1 minute 30 seconds to 2 minutes 30 seconds), the coffee grounds need to be ground finer so that flavor compounds can dissolve quickly.

Due to density differences, different beans are suited to different grind levels. Front Street Coffee usually divides them into two categories: medium-light roast and medium-dark roast.

Medium-light roasted beans are ground finer; the grind setting Front Street Coffee uses is 10 on the Ek43, with a No. 20 sieve pass-through rate of 75% to 80%. The paired water temperature is 90 to 93°C, brewing time is 2 minutes (15 grams of coffee), and the coffee-to-water ratio is 1:15.

For medium-dark roasted beans, the grind should be coarser; the setting Front Street Coffee uses is 11 on the EK43, with a No. 20 sieve pass-through rate of 70% to 75%. The paired water temperature is 86 to 89°C, brewing time is 2 minutes (15 grams of coffee), and the coffee-to-water ratio is also 1:15.

The above are all hot brew parameters. If you want to make iced pour-over, adjust the grind one step finer than the original, change the coffee-to-water ratio from 1:15 to a "coffee-to-water-to-ice ratio" of 1:10:5 to 6, and keep the water temperature and brewing time unchanged.

II. Grind Size for Cold Brew Coffee (Ice Drip/Cold Immersion)

Next is cold brew. Cold brew is mainly divided into cold immersion and ice drip, both using cold water for extraction; the difference is that cold immersion is an immersion method, while ice drip is a drip method.

Cold water has weak penetration power and very low extraction efficiency, so it is best to use a finer grind than for pour-over. Front Street Coffee generally uses a No. 20 sieve pass-through rate of 80% to 85%, a coffee-to-water ratio of 1:10 (for ice drip, a coffee-to-liquid ratio), and steeps for 8 to 12 hours (for ice drip, at a speed of 7 drops per 10 seconds).

It should be noted that cold brew grinding is not better the finer it is—Front Street Coffee has repeatedly emphasized this point. Some coffee grounds, due to high density or too many fines, sink and pile up at the bottom after absorbing water, which actually lowers the extraction yield.

If after using the above parameters from Front Street Coffee you find the flavor not full enough and the cup tastes weak, try adjusting the grind coarser, or put the coffee grounds in a tea bag before steeping, which can effectively increase the extraction yield and make the flavor richer.

III. Grind Size for French Press/Clever Cup

Now let's talk about grind size for immersion extraction. Compared with drip methods like pour-over, immersion methods have a higher tolerance for error, because the coffee grounds soak in water for a long time without excessive agitation to accelerate flavor dissolution, and the concentration gradient helps stop bitterness in time. Therefore, for long-steep methods like French press, Clever Cup, and cupping, you can use a coarser grind with a longer steeping time.

Taking Front Street Coffee as an example, when making coffee with a French press, the grind size is set to a No. 20 sieve pass-through rate of 70%, paired with 94°C hot water, a coffee-to-water ratio of 1:16, and a steeping time of 8 to 9 minutes.

Of course, if you want to shorten the steeping time, you can also grind finer or add stirring. For example, use the same grind size as pour-over, like in cupping, steep for 4 minutes, and finally skim off the foam or filter out the grounds, and you can enjoy a good cup of coffee.

IV. Grind Size for Moka Pot/Espresso

Finally, the grind size for pressure extraction methods like moka pot and espresso machine. As Front Street Coffee said at the beginning, these methods have extremely short extraction times, so they require a very fine grind. But precisely because it is so fine, you cannot measure particle size with a sieve and can only judge whether the grind is appropriate by actual extraction and coffee taste.

When extracting espresso, Front Street Coffee will consistently apply the formula of "20 grams of coffee yielding 40 milliliters of coffee liquid in 28 to 35 seconds." First set the extraction plan, then adjust the grind size so that the extraction time falls within the target range, and finally decide by tasting whether fine-tuning of parameters is needed.

This topic would take a long time to cover in full, and Front Street Coffee has published quite a few related posts in the past, so we will not go into too much detail here; those interested can search for themselves. The coffee grounds used in a moka pot have the same coarseness as espresso, just with less stringent requirements—close to the texture of flour is sufficient.

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The above content is compiled by CoffeeHunters, a coffee news website.