Grind Size Matters

Have you ever given much thought to your grind setting? Or maybe you order your coffee from us pre-ground for your preferred brew method? Knowing your coffee grounds is the baseline for great coffee. 

In this blog, we’re going to talk about the difference between burrs and blades, under and over extraction, and coarse or fine grounds. Whether you’re using a Kalita or an espresso machine, by the end of this blog you should know your grinds, of coarse!

Burrs or Blades

You might have heard of one of these terms more often than the other, and that’s because most coffee drinkers recommend using a grinder with burrs. At Cartwheel, we use a Mahlkönig EK43 and the Mythos 1 and 2 grinders which all operate using burrs. In fact, there won’t be any commercial grinders that use blades because they shouldn’t be used for grinding coffee at all. Save it for your nuts!

Using burrs provides the most consistent particle size of coffee grounds; our baristas can programme in specific grind settings depending on their needs. Burrs will usually have an adjustable distance setting, meaning that you can grind to a specific coarseness with relatively accurate consistency.

At the other end of the scale, coffee grinders that use blades are generally frowned upon due to their uncontrollable nature. A grinder with blades chops coffee into a variety of different particle sizes and may need shaking or pulsing to ensure that all the beans are being caught. Coffee in a blade grinder will stay in the same chamber as the whole beans which results in over grinding some beans, and under grinding others. This creates a lot of coffee ‘dust’ and some larger chunks we refer to as ‘boulders’, as opposed to the neat, uniform grounds produced by burrs. If you have a blade grinder, why not take a closer look at them next time you use it?

This is important because different brewing methods require different grinds – an immersion method, such as a cafetiere, which takes longer to brew, will require coarser grounds than an espresso machine – which brews relatively quickly. Control at this level is impossible to achieve using a blade grinder. But more importantly it leads us onto extraction…

Under and Over Extraction

So, what effect does a bladed grinder have on your final brew? Fine grounds or coffee ‘dust’ will allow a given amount of coffee to have a much larger surface area, meaning the brewing water can more easily enter and exit the coffee, taking the soluble coffee with it. There is a certain level of solubles in the coffee we want to take out but removing too much of some compounds will result in over extraction. 

Over extracted coffee will taste bitter and the final brew will taste too strong. It also overpowers some of the more delicate tasting notes that we encourage you to look out for in our coffees!

On the other hand, under extraction occurs when water isn’t in contact with coffee for long enough or coffee grounds are too coarse. In this case, the brewing water wouldn’t absorb enough coffee solubles, resulting in an under extracted brew. Under-extracted coffee doesn’t carry much flavour, is weak and it can taste sour and acidic because acids dissolve faster than sugars. Worst of all is that you’re leaving untapped caffeine and flavour locked into those grounds and then chucking them in the bin. 

The issue with a blade grinder is that it creates both large particles and a lot of very fine particles which effectively creates ‘uneven’ extraction – both under and over extraction in the same brew. If you’re buying coffee that’s as good as ours (shameless plug)… giving it the best treatment it can is the least you deserve to get the most out of it. 

Whilst we don’t usually recommend pre-grinding coffee, if you do use a blade grinder, we’d recommend you order the coffee pre-ground from us, because then you’ll at least have evenly sized coffee grounds. 

Of course, your next best alternative is to purchase a grinder. We’ve used the Baratza Encore for many years in our own homes; it’s the industry standard entry-level home coffee burr-grinder. Unlike other pieces of electrical home coffee equipment which are not designed to be repaired, the Encore will last for many years and spares are readily available in the UK. Find it here: Baratza Encore Grinder | Cartwheel Coffee

How We Grind

If you’ve ever bought a subscription with us, or even a single bag of coffee, you’ll know that we offer you four different ways to receive your beans! These include wholebean, filter, cafetiere and espresso. The best way to think of this list is in order of grind size, with wholebean being the biggest (intended to grind fresh at home to your own desired size) and espresso being the finest.

Below is a quick overview on how to use each size!


Whole bean coffee is how we recommend you purchase your coffee, as we intend that you will grind your own serving at home before brewing. Using this method means that the coffee will be at its freshest at the time of brewing. 

We’ve written about this before and, if you’re interested to read more, you can check out our blog on nitro-flushing to see why we recommend wholebean, and the science of oxidation going on inside your beans!

Now onto the grinds…


Filter brewers are some of the most common pieces of at home brewing equipment. We recommend choosing this category if you have a small batch brewer or if you’re using your coffee to make multiple cups of coffee using a drip method, these include the likes of Kalita wave 185, V60 and Clever dripper. 

The more cups you brew at once, typically, the coarser the grind will need to be. If you’re new to the Kalita, check out our extensive brew guide on how to use it!


You should use a medium grind size for most immersion brewers, this includes the cafetiere and the Aeropress. Contrary to popular coffee mythology, cafetieres do not require that you use an extremely coarse grind size. All the coffee grounds will sit with all of the water at once and therefore this style (immersion) will produce a more even extraction. We also reserve this grind size for drip methods designed for single cup pourovers. 

If you’re looking for a guide on how to perfect your cafetiere game, you can check our brew guide out on the website!


This is our finest grind for any portafilter, Moka pot or home espresso set-up. This level of grind is one of the finest. It’s integral that you use a fine grind for espresso. Anything too coarse will allow the water to pass through it quickly – which would result in under-extracted coffee.

If you buy whole beans and can’t get the grind quite right, use our descriptions above for under and over extracted coffee so you can tweak your own grind settings. We also recommend checking out the Coffee Compass by Barista Hustle.

As a subscriber, you’ll get access to incredible training material from Barista Hustle if you are interested to learn more. 

And if you’re confused about what might be best for your brewer, drop us a message or visit us in store, where one of our baristas will be happy to talk you through your options! 

Ps. We’ll even grind in-store orders for you if you ask!