There are so many ways to make coffee, and each one produces a distinctive style of brew.
Perhaps you love the intensity of an espresso or maybe a cup of rich French press coffee is the one for you.
Whichever style of coffee you prefer, the one thing you need to get right is the coffee grind size.
This is one of the key factors affecting what will end up in your cup.
If you want great coffee, you need to know about the grind!
Grind affects extraction rate and extraction rate affects grind
Extraction rate is one of the most important aspects of preparing the perfect cup of coffee (1).
Over 1000 aroma compounds are found in coffee, most with long and difficult names.
For the sake of simplicity, we can simply refer to them all as “flavors”.
Coffee beans are bursting with flavors, some good and some bad, and we free them by bringing them into contact with water.
Extraction rate is the rate at which they are freed.
In general, if coffee is under-extracted, it means the desirable good flavors have not yet had chance to escape.
On the other hand, if coffee is over-extracted, it means too many flavors have been liberated – including the bad ones that spoil the drink.
This means the secret to brewing the perfect cup of coffee is to control extraction to find the sweet spot between under-extraction and over-extraction.
This is where the grind comes in.
The most effective way of controlling the extraction rate and the escape of all those flavors is grind (2).
The higher the surface area of the coffee, the faster the extraction rate – meaning coarse-ground coffee has a much slower extraction rate than fine-ground coffee.
As we mentioned, there are many ways of preparing coffee, all resulting in a different style of drink.
The basic concept of combining water with ground coffee beans is universal, but each different method of brewing coffee requires a different amount of contact time – the amount of time the water is in contact with the ground coffee (3).
The longer the ground coffee is in contact with the water, the more chance all those flavors have to escape into your drink, and vice versa.
This is where choosing the correct grind for the technique you are using becomes vital.
If you are using a method of brewing coffee with a long contact time, you need to use a coarse grind.
Otherwise, the undesirable flavors will be freed along with the flavors you want in your drink, and the result will be a bitter, unpleasant cup.
Conversely, if you are using a brewing method where the contact time is short, you will need a finer grind so that all the desirable flavors don’t remain trapped.
If you use a coarse grind with a method that involves only a short contact time, you will end up with a tasteless, insipid coffee.
Don’t worry, we’ll be coming to the details shortly!
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The final aspect of making great coffee is the flow rate, the time it takes for the water to pass through the ground coffee.
Increasing the flow rate decreases the contact time and so allows fewer flavors to escape while decreasing the flow rate has the opposite effect.
The flow rate with coarser grinds of coffee is higher, so if you want to increase the contact time to allow more flavors to escape, you should use a finer grind of coffee.
If the grind is too coarse for the method you are using, the water will pass through the ground coffee too quickly without releasing enough flavors.
In this way, by changing the grind of the coffee, you can control the flow rate and in turn, the contact time, which ultimately affects the taste of the coffee produced.
French Press and Percolator – Coarse Grind
If you use the correct grind and the correct timings, a French press can produce a lovely rich coffee with an unmistakable aroma.
However, if you use the wrong grind or you leave the coffee to steep for too long, it is easy to release the bad flavors that will make your drink bitter and unpleasant.
This method involves a relatively long contact time, so the correct grind is coarse-ground coffee.
Listening to the water gurgling in a percolator as is releases the aromas and fills the room with that distinctive smell as you patiently wait for your first coffee of the day is one of life’s great pleasures.
With a percolator, the water naturally drips slowly through the ground coffee, meaning it already has a high contact time, so for this method, you also need a coarse grind.
If you grind your coffee too finely, the flow rate and contact time will increase, releasing unwanted flavors and making the coffee bitter.
Our tip is to try a slightly finer grind for a percolator than you would use with a French press.
Coarse-ground coffee is commonly described as being similar to coarse salt.
It contains distinct particles of coffee and is coarser than regular table salt or granulated sugar.
Flat-Bottomed Drip Coffee, Vietnamese-Style Coffee – Medium Grind
Flat-Bottomed drip coffee methods, including Vietnamese-style coffee, involves passing hot water through the coffee into a cup below.
When done right, it can produce a delicious dark brew with a sweet, chocolatey flavor, of course, depending on the beans you use.
Since the water passes through the ground coffee faster than with a percolator, this type of coffee requires a medium ground coffee.
If you use coarse-ground coffee for this method, the water will pass through too quickly without releasing any of the necessary flavors, and the result will be a watery, tasteless brew.
On the other hand, if you use fine-ground coffee, the flow rate and contact time will increase to a point where the unwanted flavors are also released, resulting in an inferior cup.
If the grind is too fine, the water may even become stuck and not drip down at all!
Medium grind is finer than coarse ground coffee, but individual particles can still be distinguished.
This grind looks more like table salt or regular granulated sugar.
If the water takes too long to drip through, try a slightly coarser grind next time.
Conical Filter Drip Coffee, Moka – Medium-Fine Grind
A popular way of making single cups of coffee is by using a conical drip coffee maker.
With this method, the water naturally passes relatively quickly through the ground coffee in the filter, resulting in a shorter contact time.
In order to decrease the flow time and increase the extraction, this type of coffee maker requires a finer grind than flat-bottomed varieties.
Using medium ground coffee will allow the water to pass through too quickly without releasing the flavors.
Using fine espresso grind (next on the list!), on the other hand, will increase flow time too much and should be avoided.
While conical filters rely on gravity to allow the water to drip down through the coffee, the moka, the traditional Italian coffee maker, relies on pressure caused by steam to force water up through the coffee – with a similar result (4).
Some people think of mokas as producing a kind of espresso, but this is not quite true.
The flow rate is lower and the contact time is longer, meaning a slightly coarser grind is suitable for this method of making coffee.
If you use traditional espresso grind coffee with a moka, the surface area is too great, and the bad flavors will be able to escape – and the resultant brew will be bitter.
Fairly obviously, this grind of coffee is half-way between medium grind, above, and espresso grind, below.
Espresso – Fine Grind
For many, this is the king of all coffees. Italy is world-famous for the coffee served there and it is in this country where, more than any other, brewing coffee has been elevated to an art form.
And in Italy, if you go into a bar and ask for a coffee, un caffè, without specifying which kind, it is an espresso you will be served.
Espresso is made by forcing water through the coffee under pressure and the contact time is especially short.
This means that to produce a perfect cup of rich, dark espresso with the distinctive crema on top, you need to use a fine grind of coffee, often known simply as ‘espresso grind’
If you use coffee that has not been ground fine enough, the essential flavors will not have time to escape and your espresso will be watery and tasteless.
If you use some of the coarser grinds of coffee we have discussed, this will be especially true, and the experience will be more like drinking a hot cup of dirty water than our prized favorite drink.
Espresso grind is finer than medium coffee, and at this level, the individual granules are no longer discernible.
This grind of coffee is more similar to caster sugar that we use for making cakes, but still not quite as fine as flour.
That finest grind is reserved for some less common but equally delicious coffees.
Turkish, Greek and Indonesian coffee – Extra Fine Grind
Turkish coffee, also known as Greek coffee or simply Oriental Coffee is a particular style of coffee commonly enjoyed in those two countries and the Middle East.
It is prepared from coffee beans that have been ground into a very fine powder and boiled in a special implement known as a cezve or ibrik.
Although traditionally ground by hand, to achieve such a fine grind at home, it is highly recommended to use a powered burr grinder (and we’re coming to grinders next!) since the amount of work required to produce enough powder for one brew makes it impractical to use the traditional method.
Another preparation that requires the finest-ground coffee is the style consumed throughout Indonesia.
This is a country that produces some excellent coffee and is also the birthplace of kopi luwak, the infamous “cat poo coffee”, one of the most expensive coffees in the world.
Throughout the archipelago, the traditional way of preparing the drink is to grind the coffee beans into a fine powder, to stir the coffee into hot water and then to let it settle.
The liquid coffee is then drunk, and the sediment is left at the bottom of the cup. To prepare coffee in this way, a fine grind similar to the grind for Turkish coffee is required.
Extra fine grind coffee has a consistency similar to flour, and it is impossible to see individual particles.
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Type of Grinders
How can we obtain these different grinds?
Once ground, coffee beans begin to deteriorate and the essential oils and aromas begin to dissipate within a matter of minutes.
So for the best results, you need to grind at home just before brewing.
Grinding your own beans means you can drink coffee in its optimum condition and also gives you flexibility in the styles of coffee you make.
The first and cheapest option is a hand grinder.
The disadvantage with this is that it takes time and effort to grind beans by hand, especially for the finer grinds.
Better are powered grinders.
The second option is a powered blade grinder. It uses blades in a similar way to a food blender to chop the beans.
These are inexpensive, quick and easy. However, the coffee produced is not consistently ground and so the flavor of the coffee cannot be controlled.
Another disadvantage is that the fast-moving blades can become hot, affecting the flavor.
The best option is a burr grinder, either flat or conical, which will give you evenly ground coffee with which to make the perfect cup.
They cost a little more, but if you want to do things properly, burr grinders are well worth the outlay.
If all of this seems a little abstract, check out this video that explains it perfectly!
So now you know the basics, go experiment.
Making the perfect cup of coffee is not a science, it’s an art – and something you can only improve with practice and experience.
And that’s half the fun.
We hope you now have all the information you need to start making better coffee.
If you have any tips for us, we’d love to hear from you so please leave a comment.
And if you enjoyed our article, please don’t forget to share!
My name is Kathy Gallo, Editor of Ag Ferrari, a Coffee buff. The guide you find here is designed exactly for you, and it is our hope that you find it not only interesting but also actionable.