The Flat vs Conical Burr Grinder – Defining the Differences

Work, sports, or eating stuff: we all have our obsessions. Mine is coffee (and eating stuff).

To the suburban dwellers ordering a “venti, extra whip, skinny caramel frappuccino” at Starbucks, the nuances of coffee are about as imperceivable as their mounting credit card debt. But for you – the exceptional coffee enthusiast – there is no consideration too small. Yet, when it comes to the flat burr grinder vs. conical burr grinder debate, the difference might be about as insignificant as “aluminium” vs. “aluminum.”

Today we are going to measure just how far the flat and the conical burr grinders stand apart, and see if it really does make a difference for your brew.

Fact vs Fiction

The coffee-passionate are not the best at separating opinion from fact, and have been known to regard their “taste” as a tool of impartial scientific discovery. Yet we, as passionate coffee devotees, deserve better than the speculations of the self-professed, so let’s get to the facts.

If you’d like a quick rundown on what a flat burr grinder and a conical burr grinder are, then check out this geeky but hugely informative video breakdown.

Grind Consistency

If you are currently making the switch from a blade to a burr grinder, then you are well versed in the importance of grind consistency (1).‘ This is naturally one of the first questions anyone should have in the debate between flat burr and conical burr, and it is, unsurprisingly, one of the most important (2).

To the naked eye, the difference between the grounds from a flat burr and those from a conical burr would be imperceivable. Yet, subject those grounds to the scrutiny of a microscope and another story begins to unfold. A conical burr grinder will produce grounds of two, large and small, particle sizes. Even under the finest grind setting on a conical burr, this particle size distribution holds true.

RELATED:

• The best electric burr coffee grinders
• The best hand coffee grinders of 2021
• The top prosumer coffee grinders for 2021

On the other hand, a flat burr grinder produces a remarkably even particle size, meaning that all the grounds are extremely uniform in size. For this reason, flat burrs are generally more expensive than conical burrs. Just look these Eureka coffee grinders and you’ll know. Although you may be quick to conclude that this alone elevates the flat burr higher than the conical burr, you’d be hasty in your judgement.

The dual size grounds from a conical burr, which is known as a bimodal grind (3), is necessary for a conventional espresso recipe. The smaller particles restrict the flow of water, allowing for a greater saturation of the larger particles. The even particle distribution of a flat burr grinder forces a barista to grind slightly finer than with a conical burr grinder, or to pull longer shots.

Though it may be more difficult to achieve a standard espresso pull with flat burr grounds, the ability to pull longer shots allows you to, in a matter of speaking, “break the mould” and get creative with your espresso recipes.

Grinder Waste

Another big consideration in this debate is waste. When you brew for perfection you understand that every teeny, tiny ground counts. Unfortunately, the flat burr grinder doesn’t understand this concept as well as the conical burr grinder does.

A direct consequence of the flat burr grinder’s shape is that some grounds will become trapped in the grinder (4). These trapped grounds could, depending on how regularly you clean your grinder, contaminate other batches and (ever so slightly) throw off the flavour of your brew. Conical burr grinders, because grounds flow straight down, do not suffer from this problem.

Minor Considerations

There are a few smaller aspects to keep in mind when comparing flat and conical burr grinders. Although these won’t affect your brew as much as the previous two, they are still important to keep in mind.

Price

On average, conical burrs cost less than flat burr grinders. You could easily find a high quality conical burr grinder, like the Baratza Virtuoso, for less than half the price of a high quality flat burr grinder. The mechanism in a conical burr, like the motor (which I will address in a bit) and the burr machinery, are much simpler than a flat burr, allowing for a lower price tag.

Noise

Conical burr grinders generally run at a lower RPM than flat burr grinders, which need a higher RPM to ensure that all the beans are forced into the grind chamber and out the sides. Because conical burrs don’t require as high an RPM as flat burrs, they don’t need as powerful a motor. A less powerful motor directly translates to less noise. Conicals are often much quieter than their fast-paced siblings, who are well known for their hair-raising, high-pitched whine.

Heat

Just like with noise, conical burrs also produce considerably less heat than flat burrs. Lower RPMs mean less friction, and, consequently, less heat buildup between the burrs. Because the oils in your coffee beans are very delicate, and vulnerable to drastic temperature changes. So, until you actually begin to brew, it’s best to avoid heat as much as possible to save all those delicious flavours and aromas for your cup (5).

What Does It All Mean?

Though these last few points may seem to favour conical burr grinders over flat burr grinders, the first two, grind consistency and grinder waste, are the most important in terms of your brew. Flat burr grinders are noisier, hotter, and pricier than conical burr grinders, yet they churn out a much more consistent grind.

Grind consistency can most dramatically impact the quality of your coffee (reference). However, flat burrs tend to trap more waste than conical burrs, which could then slip out in later grinds and kill the freshness.

To make it simple: a flat burr grinder is going to require a lot of maintenance and attention, while a conical burr grinder is never going to break out of that conventional espresso mold.

Final Thoughts

The difference between a flat and a conical burr grinder is minutiae. If you are comparing a quality conical to a quality flat burr grinder, both of which are clean and in good working condition, then the subtle differences in grind freshness and grind consistency would be barely noticeable.

But, for me, a good conical burr grinder still wins the race!