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Next Brew Box Shipment Date -> 24th July 2024 🗓
Next Brew Box Shipment Date -> 24th July 2024 🗓
Do you know the effects of grind size ?

Do you know the effects of grind size ?




Taste is a perceptive thing, depending on your diet, what you normally eat, what your taste buds like, we all like different things and dislike others. I hate beetroots. As an evolutionary survival mechanism, humans are wired to prefer sweet-tasting foods and avoid bitter substances. In the distant past, that helped us avoid poison and find food that provided energy.

This transfers over into coffee, some people like big beefy south american coffees like nutty and chocolate tasting notes whilst others prefer the juicy acidity of some African coffees.

Other than the tasting notes of each individual coffee, additionally every coffee can be either too bitter (a taste we like to call over extracted) or too sour and lacking (a taste we like to call under extracted). You’re always looking for that sweet spot in the middle.


So, you want your coffee to taste even more delicious, sweet, and balanced than just the tasting notes on the front of the bag. You want that incredible aroma and lingering aftertaste. And you want this every single time. There are many variables that affect how your coffee tastes: time, temperature, brew device… But the most powerful tool in brewing better coffee, assuming you have good beans and good equipment, is grind size.

Let’s take a look at why grind size is key and how you can make use of it.

The secret to great coffee lies in extraction. But what does this really mean? Well, it refers to the process of extracting the flavor and aroma compounds from your coffee beans into your hot water – and, in doing so, creating a delicious beverage. However, not all flavor and aroma compounds are the same. Some add sweetness to your coffee, others bitterness; some add fruity notes and others astringency. And they all extract at different rates. Coffee extracts in a predictable way, first your acids, sugars, bitters, and then astringency, you really don’t want it getting to the bitters or astringency part.

This means that, by controlling the degree of extraction, you can control how much of these elements make it into your beverage – or, in other words, you can determine the flavor of your coffee. This is the fundamental goal of making a great cup of coffee, whether you’re pulling espresso shots or crafting a pour over.

And grind size is a key part of this.



Several elements affect your coffee’s flavor: grind size, brew time, water temperature, the coffee beans themselves, their roast level…

Let’s define these quickly:

  • Coffee beans: Not all beans are the same. Different origins, coffee varieties, and processing methods all have a different impact on the taste of your brew. 

  • Roast level: If under-roasted, your coffee will taste sour. Over-roasted, it’ll be bitter and smoky. But in between, there’s a world of difference: light roasts tend to be fruity and acidic. Medium roasts have more sweetness. And dark roasts have a lot of body with a dose of bitterness, and typically less complex flavors. (For this reason, most specialty roasters opt for somewhere between light and medium.) 

    But it’s not just about flavor; the darker the roast, the quicker compounds are extracted. More on that to come!

  • Brew time: The longer you brew, the more you extract.

  • Water temperature: The hotter the water, the more you extract.

And then you have grind size, one of the most powerful tools for controlling extraction.

WIthout getting too scientific, grind size is one of the biggest factors in flavor when brewing coffee…exposing more surface area makes it easier for water to extract more compounds over the same period of time.


The ideal grind size will depend on many factors:

Your brewing device: Different brewing devices may require different grind sizes. Take espresso, for example: this requires a fine grind (although there’s still room for variation). French press, on the other hand, typically works best with a coarse grind.

There are many reasons for this difference. A French press is immersion brewing, i.e. it requires a long brew time, usually around four minutes. A coarser grind counteracts this by slowing down the extraction. Espresso, on the other hand, has a very short brew time, typically just 20–30 seconds, and uses pressure to force water through even the most densely packed coffee. This makes it better suited to a finer grind size.

Roast date: Never forget that coffee is an agricultural product and, just like bread or milk, is best consumed fresh. Once roasted, it will start to age and lose some of its flavors. To compensate for this, you can adjust your grind size. Alex suggests, “Increase your dose first, then consider fining up your grind, and you can liven up even month-old beans in a pinch.”

Roast levels: Will point outs that different roast levels don’t just affect which flavors you can extract. They also affect how quickly those flavors extract. Dark roasts are more soluble because they’ve exposed to heat for longer. This means extraction will be sped up. Generally, Will advises using a coarser setting for dark roasts and a finer setting for light ones.


But if grind size is just one of several factors that affect extraction, why pay all this attention to it? Because it’s arguably the most powerful factor. What’s more, grind size will affect your other variables. Take brew time and filter coffee. The brew time is the amount of time it takes the water to trickle through the grounds and out through the filter. And so, how fine or coarse the grinds are will impact on the time it takes.

“Think of a glass of sand versus a glass of pebbles: pouring the same amount of water through each, you’ll see that water takes longer to pass through sand than it does through pebbles,” Alex says.

This means that you have less flexibility with grind size than you do with water temperature, for example. The wrong grind size would have a far more drastic impact on your coffee quality.

Moreover, with pour overs and batch brew coffee, grind size will affect turbulence: how much the coffee grounds get moved around during brewing. And this also has a huge effect on extraction.

You want every coffee ground to be extracted to the same degree – or as close to it as possible. This will make coffee quality more controllable and more repeatable. This means that all the grounds need to spend the same amount of time in the water.

A little amount of turbulence is a good thing: it will move the grounds around, ensuring they are all exposed to the water. However, you don’t want the turbulence to push the grinds up the walls of the filter, where they will sit out of reach of the draining water and not be fully extracted. This will lead to sour notes in your coffee – and, unfortunately, it is more likely to happen with finer grind settings.
The wrong grind size cannot just be compensated for just by adjusting other variables, because it has affects so many other factors. So, once you’ve confirmed your ratio of coffee to water, look to grind size. If you’re brewing filter/batch brew coffee, this will also dictate brew time. And only after that should you look at temperature, turbulence, and so on.

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