Coffee is coffee, right?
Actually, picking the right coffee is not a straightforward task. Besides deciding on a coffee bean for the flavor, you also need to consider grind size/coarseness.
Why Does Grind Size Matter?
When it comes to making coffee, there are a few basic ingredients that you need:
- Roasted coffee beans
- Receptacle (AKA, the humble coffee mug)
But, as you probably already know, shoving these things together and hoping for the best doesn’t make a good tasting cup of coffee.
So next we need to master a brew ratio, e.g. the right temperature, the right coffee beans, the right volume of coffee beans, the right volume of water and the right extraction time.
Most of our modern coffee machines will get this right for us. Even the manual French press and Moka pot are specific sizes to stop us going horrifically wrong when it comes to this ratio.
But still, a cup of coffee can taste terrible.
The solution? We refine our coffee coarseness.
When we talk about the coarseness of coffee, we actually mean the size of the coffee beans we are using. A very coarse grind is where we grind a little, resulting in large chunks of coffee beans. A very fine grind is where we grind down our beans until they’re a gritty powder texture.
With a coarse grind of coffee, our hot water binds to the outside of the individual grinds. It absorbs the flavor as it slowly penetrates to the center of each grind.
With a fine grind of coffee, our hot water binds to the outside of the individual grinds in the same way… however, as the grinds are much smaller, the water can penetrate and extract the flavor much quicker.
Fine grinds = quick extraction time
Coarse grinds = slow extraction time
And that is simply why coffee grind coarseness can have a HUGE effect on the flavor of our finished coffee drink.
So, Which Grind Size Do I Need?
Some coffee makers are better suited to different ground coarseness levels – and of course, the beverage you’re trying to make will also dictate the grind size you need. Generally, if your extraction method is quick you need fine grinds, if it’s slow you need coarse grinds.
Use this short grind size table to find out where you should start – don’t be afraid to try out slight variations in your grind size to obtain a premium coffee taste!
You need fine to medium-fine grinds with your Aeropress, although most Aeropress models are adjustable. An Aeropress works in a similar way to an espresso – forcing water through your coffee grinds quickly rather than letting them brew. For this quick extraction, you need finer grounds so that the water has a chance to really penetrate the coffee molecules.
Coarse grinds in an Aeropress will result in seriously under-extracted coffee unless you’re going to wait for ages for it to brew.
Drip coffee brewers
Drip and pour over methods (where you add water to your coffee grounds and let gravity do all the work) generally require medium-fine grounds. While the water isn’t pushed through as quickly as the Aeropress and espresso machine, there’s still nothing stopping the water from running straight through the coffee.
A medium-fine grind ensures that the slow, steady stream of water extracts enough flavor without over-extracting.
Real espresso machines require 9 bars of pressure to pull a shot. These machines are expensive and take up quite a lot of kitchen worktop space. Make sure you actually have an espresso machine and not a coffee maker that makes extra strong coffee, before using fine grinds in it.
Fine ground coffee is essential for espresso machines. Water is forcefully pushed through grinds in 30 seconds – consistency in grind size, distribution in the group handle and correct ratio of coffee volume is vital. If your grind is too coarse, you’ll have under-extracted coffee. If you lack consistency, you’ll have both under-extracted and over-extracted coffee in the same cup!
You will need coarse grinds for your French press. Unlike drip, espresso and Aeropress methods, your French press soaks the coffee grinds in water for an extended period of time (usually a few minutes, which is quite long in the world of coffee-extraction).
If you use finer grinds, the water has better access to the coffee on a molecular level, extracting those coffee flavors and oils much quicker – leading to over-extracted coffee. As a general rule, if you struggle to push down the plunger, your grounds are too fine.
Generic, automatic coffee makers
Medium to medium-fine grinds are usually what’s best for these coffee makers – whether they drip or use some force to push the water through the grinds. Most basic coffee makers (the boring kind you find in offices across the world) are not operated by Coffee Dorks like us. They will have a set extraction time – the key is to find the right grind size and stick with it. This applies to basic brewers like the BUNN GRB Velocity Brew: it’s not programmable for different extraction times, so once you know that it produces it’s the best coffee with a medium grind from a particular brand, don’t deviate!
Your Moka pot, or stovetop coffee maker, usually requires a fine grind like an espresso machine. A Moka pot turns water into steam that travels through your coffee grinds into the top compartment, ready to be poured.
It may not be as fast as an espresso machine, but fine ground coffee is still essential. For the steam to extract and lift through the coffee, the grinds need to be fine enough to let the water molecules through. The combination of a fine grind and long extraction time usually results in very strong coffee.
What Are Coarse Grinds Best For?
Coarse grinds are best for a French press – which certainly limits you when it comes to making coffee beverages. Latte, cappuccino, flat white… all of these coffees are made with espresso, which uses fine grinds.
But, you can still use your coarse grinds and French press to make some tasty coffee drinks. Once you get the coarseness right for your French press, you’ll love your homebrewed, barista-quality coffee.
If your coffee is coming out too sour, that usually means you need to make your coffee grounds finer. If it’s too bitter, you’ve over-extracted and you either need to reduce your immersion time or use a coarse grind – or both.
Types of Coarse Grinds
You have 2 ways of getting coarse grinds – purchasing pre-ground coffee or buying coffee beans to grind yourself.
- Very convenient
- Perfect sized packages
- Great consistency
- Won’t taste as fresh
- More expensive
Grinding your own coffee:
- The taste will be out-of-this-world
- Very rewarding, especially with a manual grinder
- Gives you better precision to get the perfect grind for your coffee maker
- Requires a grinder with burr blades
As Coffee Dorks, we all love grinding our own coffee but often buying pre-ground beans is just more convenient. Whichever you decide to do, make sure the machine you’re putting the coffee into is worth it!
Anthony is a professional barista in the city of Chicago. He has written for many online publications on various topics related to coffee.