4 days ago
Is Particle Analysis the New Key to Great Coffee? We Tried It Out
The performance of coffee grinders used to be a mystery, unless you knew someone at a lab. We used a new tool to analyze our top coffee grinder picks, and maybe make better coffee. Courtesy of DiFluid; Getty Images
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I don't mean to be dramatic when I say coffee grinders are both the biggest mystery in coffee, and also coffee's biggest hive of technological invention.
If you find yourself in the online rabbit holes of the coffee world these days, you'll almost certainly encounter a bean geek eager to tell you a secret. The secret is that your coffee grinder is more important to how your coffee tastes than your drip brewer, and also more important than your espresso maker.
This idea makes some sense. Just like temperature and time and pressure, the size of your coffee grounds will determine how fast your brewer can extract flavor—and maybe even which flavors get pulled out. Uneven coffee grinds, with lots of ultrafine particles or giant boulders, will cause uneven extraction. This in turn will result in bitter or muddy coffee, or a failed shot of espresso. Photograph: Matthew Korfhage
But until pretty recently, grinder tech had been ignored by all but the nerdly few, says Jordan Michelman, cofounder of coffee website Sprudge, which for 15 years has been the coffee industry's home page. (Michelman is also a contributor to WIRED.)
'It's really just in the last decade that a lot more attention has been paid to grinder minutiae, grinder results, grinder tech,' Michelman said, noting it's now become a frenzy. 'There's been quite a lot more advancement, technological innovation, new tools, and new stuff in the world of grinding than there has been in espresso [machines]."
Now, it's rare to find anyone who cares about coffee using a cheap, old-fashioned blade grinder—basically a blender for coffee—which roughly chops coffee beans with spinning steel. The new wisdom is that only burr grinders will do. Conical burrs are like a many-angled drill bit, crushing and funneling and finally cutting each bean. Flat burrs, meanwhile, are like spinning wheels of death that rotate against each other at a set separation.
But even if you buy the expensive grinder, it's hard to know how well a coffee grinder is actually working, or even the basic rules behind what types of grinders create what flavors. Do conical burrs make coffee taste more like chocolate? Does a flat burr love fruit? Maybe. Technical-minded coffee influencers like Lance Hedrick have been pretty open about throwing up their hands when it comes to the actual science of it all. The science, quite frankly, isn't in. Grinders are lore . They're a shared culture of subjectivity.
When I test grinders, much of the hard work is often done simply by taste test, comparing flavors yielded by different grinders with the same beans. I've used magnifying lenses to look at the evenness of grinds, scratched my head over static and clumping, and spent untold hours comparing notes with other coffee obsessives online.
But up to now, about the best objective home tool for assessing grind precision was to pour coffee grounds through a set of sieves, and see how much coffee you still had left. Not a Leibovitz-caliber portrait, but it's something. The Age of Home Coffee Grinder Analysis Has Arrived Photograph: Matthew Korfhage
Imagine my excitement, then, to finally have a piece of equipment that could potentially depict how well a coffee grinder works in granular detail. Specifically, I've got a DiFluid Omni ($900), a new device that promises something heretofore unknown: the chance for home coffee geeks to graph out the particle size distribution of a batch of coffee. (It also has a colorimeter, to assess the lightness or darkness of a roast.)
Until recently, you'd have to shell out thousands of dollars to conduct particle size analysis on a batch of coffee—or maybe know somebody in Germany who runs a university lab. The Omni comes in at about a quarter of the price of the next closest device I've found. Still a lot, but it's an amount of money that many people actually possess. And the Omni promises to graph particle size with more reliability than previous attempts at home analyzers.
And so for kinda the first time, it's possible for someone at home to assess how good a grinder is. Even a few years back, says Michelman, having tech like this at home would have seemed 'unthinkable.'
Now that it's thinkable, we figured we'd put our favorite coffee grinders to the test—the grinders that the WIRED Reviews team has been recommending based on long experience. The coffee grinders we've been not just recommending but also sometimes arguing vociferously about behind the scenes. Some questions now have answers.
So who would prevail? The Fellow Opus or the equally priced Baratza Encore ESP? Are higher-end burr grinders demonstrably better than budget grinders? And does the Omni actually work as advertised? The results are a little complicated. But I've learned more about my favorite coffee grinders this month than in the entire past year.
For each grinder, among seven I tested during this first round of particle analysis, I kept it simple. I used the same coffee beans, from the same batch: A Stumptown Single Origin Colombia whose flavor I know well, with its roast date printed on the bag.
I tested a medium grind for drip or pour-over coffee. And I tested nearly the finest grind each grinder was capable of, which usually was an espresso grind. (Just in case the actual finest grind was an outlier, I moved up a notch or a few notches coarser, for each grinder.) I then ran at least five tests for each grind size, for each grinder, to get a cumulative particle distribution. To collate and visualize this data, I relied on an app that's still in beta testing as of August 2025: DiFluid's CoffeeOS app. Photograph: Matthew Korfhage
Each test involved using a wee sampling of coffee grounds, totaling one-64th of a teaspoon or less. To run the test, I spread the grounds across the white circular base of the Omni. This could be done using Omni's brush, or the device's vibration function. Both methods were recommended by DiFluid, but I found that vibration worked better for fine grinds, while coarse grinds were better off being dispersed by the brush.
Then I placed the Omni's top onto the base: The top of the device has a camera whose lens faces the circular base with the coffee grounds on it. The camera captures the size of each ground, assuming the grounds are dispersed appropriately.
The results weren't always perfect: It's hard to stop coffee from clumping. But they were illuminating. DiFluid's app is still in beta, so I'll wait to publish full results of particle size analysis—and in the meantime keep collecting more data. But I will offer a number of early impressions. Fellow Opus vs Baratza Encore ESP: Which Is Better?
Spoiler: An app can't tell you what grinder is best. But it does help tell you which one's more precise, and it gives you insight into how each grinder develops flavor at different grind settings. And among all of the electric coffee grinders I tested, the Baratza Encore ESP proved itself to have the most precise results at very fine grinds. Courtesy of Matthew Korfhage
On fine grinds, about 30 percent of the ESP's coffee grounds huddled in peak range—the most concentrated result of any electric grinder I tested. At a medium grind level, the ESP wasn't quite as tightly grouped—and there was a fair amount of coffee fines. In my experience with the ESP, these contributed more to full body than bitterness.
Meanwhile the Fellow Ode Gen 2, a flat burr grinder we've long held as our favorite for drip coffee, produced a textbook-looking normal distribution at medium grinds—a mix of precision and nuance—but a flat distribution at finer grinds. Courtesy of Matthew Korfhage
The biggest surprise was the Technivorm Moccamaster KM5, a flat burr grinder I hadn't tested till this past month. The Moccamaster showed quite precise results across the board—rivaling the Encore ESP at fine grinds and the Ode Gen 2 at grinding for drip. Moccamaster is a much-trusted coffee brewer brand, of course, known for its analog precision. But it's not known for grinders, and without this particle analysis I might not have clocked how well it did. Courtesy of Matthew Korfhage
In fact, multiple results were surprising. The conventional wisdom is that flat burr grinders are precise, and conical burr grinders are more likely to show a balanced blend of grind sizes—and therefore bring out sweetness, depth, and chocolate. But raw data from particle analysis showed mixed results even for the same grinder, depending on the coarseness or fineness of the grind setting.
And so the same grinder might evince austerity at one grind level, and sweetness at another. At coarser grinds, the Kingrinder K6 hand grinder behaves much like the Ode, with a nearly textbook bell-curve distribution surrounding a central peak—as if plucked from questionable studies about human ability. Courtesy of Matthew Korfhage Photograph: Matthew Korfhage $129 $99 (23% off)
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But when I dialed the K6 tighter to espresso-fine grinds, the K6's curve compressed to what looked like a slender butte: Grind sizes stayed fairly even, across a tightly compressed range. This would indicate precise and aromatic pour-over, but chocolatey espresso—maybe the best of both worlds. These results were backed up by my own taste test. But Imprecision and Variability Reign
And yet, precision is relative. A surprise from this testing was the extreme variability of coffee grounds within each sample, among all grinders tested. Coffee grounds aren't one size or another: Rather, they live on a continuum. The sweet spot for brewing coffee in any given style is a window of just a few hundred microns—and yet, the standard deviation for the grinders I tested was rarely less than two hundred microns.
Coffee grinders invariably spit out a range of both large and small particles. A range of coffee particle sizes isn't bad, necessarily: This can lead to balance, depth, and complicated toffee or chocolate notes. Tight particle distributions will more likely express more specific aromatics, like bright cherry or funky plum. The one universal is that you don't want too many extra tiny particles (which can lead to bitterness), or extra large boulders (which lead to muddled, muddy flavor).
I had trouble getting useful results from the Omni at first. The device doesn't always differentiate between coffee grounds when they're too close together, and its base has a quite small surface area, which makes for a small sample size. Combined with the broad variability among samples, it's tough to draw helpful conclusions from any individual test—enough so that I initially thought the DiFluid Omni was a bust. Photograph: Matthew Korfhage
I sent worried emails to DiFluid's customer support to this effect, and was told at first to try using smaller scoops of coffee to avoid clumping. I tried spritzing coffee beans with a tiny bit of water before grinding, to avoid static electricity. I also shook and stirred the grounds before sampling, to declump further—and tried out multiple distribution methods to spread the coffee grounds optimally across the Omni's base.
But in the end, the problem wasn't clumping: It was sample size. To mitigate this, you'll need Omni's CoffeeOS app, which is still in beta but accessible through Discord. Pair your phone to the device, and the app can collate results from multiple tests to build a more robust distribution curve. By the time you conduct five or more tests pulled from the same batch of coffee grounds, patterns begin to emerge.
If DiFluid Omni is still a bit fussy to get results from, it offers the best snapshot I've seen of how—and how well—an individual coffee grinder operates. Presumably, DiFluid will keep improving on its software and firmware. Meanwhile, competitors may also enter the market at an accessible price point. This'll all be good. Already, I have a brand new way to understand why my coffee tastes the way it does. Michelman, the cofounder of Sprudge, says tools like this weren't conceivable for home coffee drinkers even a couple years ago.
'These are tools that were once only the sort of thing you could imagine having access to in, like, a successful coffee bar with dough to spare,' he said. Particle size analysis was available only to 'a fraction of a fraction' of people in the coffee industry.
On the one hand, a home particle size analyzer for your coffee grounds is so deep down the nerdhole it's hard to even find the exit. On the other, it's a future that would have once felt unimaginable.
