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Coffee Grinders: Conical Vs Flat Burrs
What is the difference and which one is better for your needs?
Published November 22, 2021
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Susan Rov
Coffee experts@The Coffee Lab
The grinder is one of the most important parts of your coffee set-up that has a significant impact on the taste of your brew.
A bad grinder that produces uneven coffee grounds will cause inconsistent extraction with some of the grounds being over-extracted while others are under-extracted resulting in a muddy taste in your cup.
Selecting a grinder with burrs rather than blades is the right decision in improving the consistency of your cup.
But the decisions don’t stop there.
True coffee geeks know that there are two types of coffee grinders, and depending on their shape, you can choose between a conical and a flat burr grinder.
Read this article to find out what are the key differences between these two types of grinders, in terms of consistency, temperature, noise levels, and retention as well as discover which one is more suited to your needs.
Reasons For Selecting A Burr Grinder
Compared to blade grinders that chop the beans, both conical and flat burr grinders use pressure to grind your coffee.
Both flat and conical burr grinders use two rings that move against one another with jagged edges and as the coffee goes through the rings, it is ground to a uniform size.
This results in fewer grinds or tiny fragments in your ground coffee, a more uniform grind, evenly extracted coffee and consistent taste in your cup.
Upgrading to a burr grinder from a grinder with blades is going to improve the taste of your morning coffee, but what are the differences between conical and burr grinders?
Conical Grinder Vs Burr Grinder
In a conical grinder, there is one cone-shaped ring that sits inside an outer burr that is circular and hollow and the beans are directed down the vertical path at a slight angle as they’re being ground by the sharp teeth.
A flat burr grinder consists of two flat rings with angled teeth that lie on top of each other. The two rings are horizontal to the ground and the beans drop between the burrs as they’re being ground.
Differences And Things To Consider
While both grinders will provide a uniform grind for your coffee, there are slight differences that can affect which grinder would be a better fit for you. Let’s look at them in more detail.
Grind Consistency
The grind consistency is the most important factor to look at when selecting the coffee grinder and there is no doubt that selecting a burr grinder, instead of a blade grinder, will improve the consistency and taste of your coffee.
But when it comes to the grind consistency between the flat and conical burrs, flat burr grinders will produce a better result, which is one of the main reasons why they are typically more expensive than conical burr grinders.
Because of the differences in construction, the flat burr grinders require the parallelism of the burrs to produce uniform beans, which is much easier to achieve than conical burrs, which require the perfect centricity and alignment of the burrs.
Bimodal Vs Unimodal Distribution
The conical grinders produce a bimodal distribution of the coffee grounds which means that if you were to look at the grounds more closely, you would see that they produce two sets of particles, one smaller and one larger in size.
Traditionally, it was believed that the bimodal distribution is better for brewing espressos, with the smaller grounds restricting the water flow and allowing the larger grounds more time to be extracted, providing a balance between the bitterness and sweetness in the cup.
Flat grinders, on the other hand, produce a unimodal distribution, where all the coffee grounds are of the same size. With no need to balance the flavors, the same extraction produces great taste in espressos and other types of coffee.
Temperature
When it comes to heat retention and maintaining the same temperature in the grinder, flat burr grinders are worse than conical grinders.
Since flat burrs require more power in order to grind the beans inside the machine, they can heat up more easily, which can be the case, especially with the cheaper grinders.
The changes in temperature lead to inconsistencies in grind size, quicker extraction, and altered taste of your coffee.
If you’re using the grinder in a busy cafe, where the temperature rises as the place get busier, flat burr grinders will absorb some of that heat causing a faster extraction.
That’s why baristas will need to pay more attention when using a flat burr grinder and adjust the grind throughout the day.
But if you’re using the grinder at home, only a couple of times a day, the temperature of the burrs won’t be affected to a significant degree, whether you have a flat or a conical grinder.
Retention
The retention means how much coffee is left behind in the machine after grinding. The retention can vary the weight and alter the extraction process and if the beans get trapped in the grinder, it can throw off the flavor of your shots.
Further, if some of the old coffee grounds stay in the machine and the stale coffee gets mixed with the fresh grounds when preparing the next shot, this will cause inconsistent extraction and flavor.
Since the electric conical burr grinder moves the coffee vertically and is therefore helped by the force of gravity, it will retain fewer coffee grounds than the flat burr grinder. But the differences also depend on the type and quality of the specific grinder you choose.
Ease Of Use
Since the flat burr grinders require more power and run at a higher RPM, this causes that they are much louder. While the noise depends on the brand of the grinder, in general, the conical grinders will be quieter and can be more suitable to use in quieter households.
Because of the higher retention, an espresso grinder with flat burrs requires more adjustments during the day. This can be crucial for baristas but if you are just brewing coffee at home a couple of times a day, this won’t make a significant difference.
Beyond The Burr Shape
The burr shape is not the only factor that determines the performance of your burr grinder. The construction, speed, ventilation, motor quality, as well as materials used for the machine, will have a significant impact.
One of the differences in which you can further distinguish burr grinders is whether they are made of ceramic or steel materials. While the ceramic burrs stay sharper for longer, they can be also more prone to cracking, but the differences are very subtle.
The Verdict: Flat vs Conical Burr Grinder
Choosing a burr instead of a blade grinder will make your grind more consistent and improve the taste of your coffee.
Deciding whether the flat or conical electric burr grinder is better for you, will depend on your requirements, the model, and whether you’re planning to use the grinder at a cafe or just for home brewing.
But in general, grinders with flat burrs tend to be more consistent, more expensive, noisier and can be prone to heating up as well as retaining some of the grounds.
On the other hand, conical grinders are quicker, cooler, cheaper, and tend to be more consistent.
About the author
Susan Rov
A retired barista who turned into a writer. I love discovering coffee flavors and learning more about the magic bean.
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