There are many fine nuances that go into a perfect cup of coffee, but one which we at Niche Coffee are particularly keen to explore is that of grinding. Our Niche Zero and Niche Duo grinders have been developed using the science of good coffee, so it stands to reason that we have a thing or two to say on the subject. If you’ve ever wondered how grind size affects coffee, you’re in the right place.
How coffee grind size affects taste
Coffee preparation is often described as both a science and an art, and this is true. It’s a science because at its core, this is chemistry, but it’s also an art because anything where taste is part of the final test is subjective. When you take a sip of a really good cup of coffee, there’s something almost magical about the process that brought it to you - it’s like the stars aligned. So, what is it about the grinding process that can help you achieve the perfect cup.
When hot water meets ground coffee, it begins to dissolve the soluble compounds within the coffee particles, which is a process known as extraction.
As water flows through the coffee bed, it extracts a range of compounds; acids and aromatics are dissolved first, followed by sugars and soluble oils, and finally the more bitter compounds if extraction continues too long.
In coffee brewing, we often discuss under-extraction and over-extraction. Under-extraction means that the water has passed through the coffee too quickly and does not have enough time to extract more than that first layer of flavour - the result is acidic coffee that’s often sour. Over-extraction, conversely, means that the water has passed through the coffee too slowly and has therefore extracted too many of the soluble compounds from the coffee. When this happens, the bitterness will overpower the desired flavour of the coffee.
What does grind size have to do with extraction? Well, quite a lot - we need a balanced grind size.
Finer grinds have a greater surface area because there are more grinds, which means more coffee is exposed to the water and more soluble compounds can dissolve. Also, as the grind gets finer, the coffee bed becomes more compacted, which slows down water flow, essentially acting like a dam. Both factors increase the time the water is in contact with the coffee, therefore increasing the extraction.
With coarser grinds, the surface area is smaller, and the coffee bed is less compacted. In this scenario, water can pass through the coffee quickly. The quicker the water passes through the coffee, the fewer flavour and aroma compounds are extracted.
The key is balance: a grind size that offers enough surface area for optimal extraction without restricting flow.
“So, I just need to find the one perfect grind size and my coffee will be perfect every time?” Sadly, it’s a little more complicated…
Different grind sizes for different brewing methods
When you make French press coffee, you seep the coffee grinds in the water. The water does not pass through the grinds as might happen with other brew methods; this is a flood, not a river. As such, fine grinds will quickly give up their flavours and over-extraction is almost a certainty. Therefore, you need larger grinds - think rocks, not pebbles.
However, with espresso, a tight puck of packed grounds has water forced through under pressure. There’s no flooding, but a hot stream of water trying to take what it can from each particle as it passes. Here, the coffee needs to resist the water in order to extract the flavours. If the grinds are too coarse the water will pass through with ease and the coffee will be under-extracted.
There is, of course, a range of middle ground brew methods. Consider the V60 pour-over, that has water moving past the grinds but in a slower fashion to that of espresso, with occasional bouts of flooding. Here, a medium grind is necessary for a perfect cup.
How do you know what size coffee grind to use?
Balancing your grind size to your brewing method is essential if you’re going to make barista-quality coffee. The following outlines some general guidance around grind size, but factors such as where the coffee was grown, how it was roasted and how long ago the coffee was roasted will all impact the exact size needed to get the best result. You may find that adjusting your grind setting coarser or finer will yield more favourable results.
Coffee grinds can be measured in microns (µm). A single micron is 1000th of a millimetre.
Grind size guide (in microns)
| Grind size | Micron Range |
| Very Fine | 100–200 µm (one tenth to one fifth of a millimetre) |
| Fine | 200–400 µm |
| Medium-Fine | 400–600 µm |
| Medium | 600–800 µm |
| Medium-Coarse | 800–1000 µm |
| Coarse | 1000–1200 µm (equal to 1 to 1.2 mm) |
What about strength? Does a fine grind make for stronger coffee?
If you are looking for a stronger coffee - more flavour, more caffeine - then yes, a finer grind does make for a stronger coffee. This is especially true if you are using a brew method that includes steeping as the water has the time to extract more from each soluble coffee solid. However, care must be taken to avoid over-extraction. Chances are that you’ll get stronger coffee but it’ll be bitter.
There are better ways to get a stronger coffee than relying on grind size, however, especially if caffeine is your goal. Increasing the coffee to water ratio - using more coffee relative to the volume of water - or lengthening brew time are more effective methods of creating strong coffee than grind size alone.
How to get a consistent grind at home
Your coffee grinder is the most important piece of coffee making equipment, forming the basis for the drink. The best beans ground badly will not be smoothly extracted and have poorly defined taste, no matter how careful you are with the brewing method.
- Use a burr grinder - Blade grinders produce almost random grind sizes, with little consistency and no ability to dial in your grind. Burr grinders will give a much more consistent grind size that is a must for consistently making delicious coffee.
- Seek zero retention - When coffee is left in the grinder, it can contaminate your next grind with stale coffee grounds which have been left over from your previous grind (much like if you left a fresh loaf of bread out for a few hours). Zero retention means no coffee remains in the grinder, leaving you with clean equipment for next time.
- Experiment and note results - Measure your coffee, adjust your grind, and note the results to dial in to the perfect drink. It’s therefore essential to choose a grinder that is consistent and reliable.
As you expect, with our healthy balance of science and art, Niche Coffee grinders excel. The Niche Zero and Niche Duo grinders have been developed to perform with exacting precision, producing that near-perfect grind that you’re looking for with virtually zero retention.
The Niche Zero uses conical burrs which offer a bimodal distribution of grind size, which is a mix of larger and smaller grinds. This variety in grind size can often lead to coffees that have a thicker, more syrupy mouthfeel like traditional espresso.
The Niche Duo uses flat burrs which delivery unimodal distribution of grind size – where each particle is more more consistent. This can lead to much cleaner cups of coffee that are ideal when brewing filter.
Professional grinding with Niche Coffee
Upgrade your coffee creation with an accurate grind size. With a Niche grinder in your setup, you give yourself the best chance of a perfect cup of coffee.
For more brewing tips that will refine your skills, explore our guides on making delicious freshly ground coffee at home
