How Does Grind Size Affect Your Coffee? Taste and Brew Method

Are you wondering why you can buy coffee ground to different sizes or why a coffee grinder is adjustable? Here’s what you want to know.

Coffee beans are ground to different sizes because different brewing methods require the coffee particles of different sizes to work best. It’s possible to deviate a little from the recommended particle size for a certain brewing method to influence the taste of the coffee.

How that works exactly and how you can use it to change the taste of your cup is explained below.

What is grind size?

In coffee world “grind size” means how big all the coffee particles are after grinding your whole beans. No matter if you grind your own beans or not, they have to be ground at some point to be able to brew coffee.

Suggested: What is the purpose of a coffee grinder?

To turn whole coffee beans into a powder, a coffee grinder is used. Most coffee grinders can be adjusted to produce coffee particles of different sizes. They won’t be all perfectly the same size but good grinders get pretty close. Average quality burr grinders have a wider distribution of particle sizes but usually good enough for most coffee brewing methods.

The grind sizes produced by most grinders can range from very fine like powdered sugar to coarse like coarse sea salt. Why should you care about this? Find out next.

Why grind size matters

The fact that grind size is a point of discussion alone will tell you that it’s probably important when brewing coffee. You can buy coffee ground to different sizes in the supermarket and almost all coffee grinders will have an adjustment so you can change the size of the end result. So you probably got an idea it’s important but why exactly?

There are a few reasons why the grind size matters:

• Brew method
• Extraction
• Flow rate
• Taste

Brew method

Different brewing methods require different grind sizes to make coffee optimally. Espresso needs to be very fine to provide the resistance you need in an espresso machine but also because you want to brew a very strong cup with a small amount of water so it has to be extracted really quickly (more on that below).

In a French press you have more time to brew the coffee and the filter isn’t super fine. You don’t want too much residue in your cup so using a coarser grind works well for this. Read more about which grind size is good for which brew method here.

Those are just two examples but you can see different brewing methods have very different requirements for how coarse the grinds have to be. There is an average grind size that’s generally considered for a certain brewing method. However, there are a ton of other factors that would require you to deviate slightly from the prescribed.

How you like your coffee and the specific beans you’re using could make you change it up a little. However, the starting point is still the average. From there you can change how you like them. You can read more about how to do that at the bottom.

Extraction

Besides playing with the brew method you’re using, grind size also impacts extraction. We are all familiar with extraction when brewing tea because it’s a bit more visible with tea. The longer you steep the tea leaves, the stronger the tea gets. Coffee is very similar. However, with coffee we don’t only use the time but also how fine the grounds are to speed up or slow down extraction.

All coffee beans have a certain amount of soluble material. That soluble material is what dissolves in the water and brews coffee. Extracting the right amount of soluble material from coffee beans is the key to brewing good coffee. That’s because if you extract too little, you get weak, sour coffee. But if you get too much, you get a harsh bitterness. The trick is to get the extraction just right so you get a balanced taste.

That’s where grind size comes in. Brewing with a whole coffee bean doesn’t result in good coffee. If you’re lucky you’ll get slightly brown water but that’s it. That’s because whole beans don’t have enough surface area for the water to extract from. This is why you grind coffee in the first place. So you can probably already see where this is going.

The finer you grind the beans, the more surface area there is and the more water can touch the grounds at the same time. This means the extraction is faster. This is true for every brewing method but of course the ideal size is different for every brewing method.

Suggested: What happens if coffee is ground to coarse?

For example: when you make an espresso, you want to extract quite a lot of grounds into a little bit of water and a short time. For that reason you need the grounds to be very fine compared to other brewing methods. But with cold brew, the water is in contact with the grounds for many hours so you can use coarser grinds.

Flow rate

Another way the grind size impacts the brewing is with the flow rate. The finer the coffee is ground, the closer the particles are together with smaller gaps in between. This means the water can flow through slower.

So you can use the grind size to influence how fast the water flows through the grounds. This is only an concern with brew methods where the water actually flows through a bed of coffee like espresso and pour over. For immersion brew methods the water just hangs out with the water for a while so it doesn’t flow through the coffee. So for immersion brewers like a French press, this doesn’t make an impact.

Suggested: Are espresso and coffee grinders the same?

For percolation brewing methods like a pour over, it does matter quite a bit. Because the water only gets a short time in contact with the grounds, a few seconds extra makes a big difference. More time in contact with the grounds means more time to extract the grounds.

This compounds what I’ve explained above about the increased surface area. So grinding finer won’t only make the water flow slower and increase the contact time, it also creates more surface area on the grounds to make extraction faster. So in brew methods where the water flows through a bed of coffee, changing the grind size has a compounding effect.

How to use grind size to change the taste of your coffee

The brew methods and grind size affect how the coffee grounds are extracted and what gets into your cup. You can use this to change the taste balance of your coffee. The brew method and beans you use of course largely decide what the coffee tastes like but the grind size can impact the balance and strength of the final brew.

So above you can see why the grind size matter and you probably already have some ideas of why the grind size is important and how you can change it to change the taste of your coffee. While you can’t deviate dramatically from the average grind size for a specific brew method, small changes can have a big impact and be enough.

In general, here’s what you need to know:

• Coffee is too sour: The grounds are under extracted which means you should grind finer.
• Coffee is too bitter: The grounds are over extracted which means you should grind coarser

However, you have to stay within the limits of your brew method. Sometimes

If you’ve played around with the grind size and you can’t find a setting you like, there could be a few things going on:

• You just don’t like coffee brewed in that particular way. If you’re brewing espresso, try a pour over instead and see if that’s more your style.
• You don’t like the type of beans you’re using. Buy coffee from a local roaster to get fresh beans. Also, roast level makes a big difference in taste. In general; the lighter the roast, the more acidity and fruitiness. The darker the roast, the less acidity and less depth of flavor but more bitterness and heavier body. If you keep having problems with bitter coffee, try a lighter roast or;
• Grind uniformity is bad. Read more below.

Grind uniformity

Another closely related term you might run into is ‘grind uniformity’. This means how wide the size distribution of the coffee particles is. Coffee grinders don’t produce grounds with particles that are all exactly the same size. Some particles will be a little bigger than average, some a little smaller.

You’re probably familiar with a bell curve. Coffee grounds have somewhat similar distribution. That means that the size of the vast majority of particles falls around the average but there are some smaller ones as well. Usually burr grinders are pretty good at taking care of particles that are significantly larger though.

Better coffee grinders produce more consistent grounds which means the particle size is concentrated much more and closer to the average. Some people pay big money for high-end coffee grinders. That’s because a higher grind uniformity is good for the taste of coffee in general.

It’s good for the taste because you can hone in on the right grind size with more accuracy. If your grinder produces a lot of particles that are finer than you set the grinder to, it’ll seem more bitter than it should. That’s because the tiny particles extract quickly and give up their bitter compounds. That will result in you grinding a bit coarser but that could bring up the average too high and you get sour on top of the bitterness.

The more uniform your grinder grinds, the less of the fines you get. This means less bitterness. That allows you to grind a bit finer without the harsh bitterness and make stronger coffee with less grounds.