If you're often the first one awake and want to make a good cup of coffee without upsetting all the late sleepers in your house, the Krups GX420851 is one of your best chances at avoiding an altercation. On top of offering above-average grind consistency, it is one of the most innocuous grinders we tested when it comes to sound emission. Its low hum is much less likely to wake up anyone in an adjacent room than most of the models on the market. Plus, it generally sells for a relatively reasonable price.
Krups GX420851 Review
Pros: Quiet operation, good grind consistency, great for pourover
Cons: Can produce enough static to hang onto grinds, not great at the extreme ends of the grind spectrum (coarse and fine)
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Our Analysis and Test Results
Offering impressive quiet operation, the Krups GX420851 is one of the few grinders we've found that doesn't elicit pangs of guilt when used while housemates are still asleep. We can't guarantee it won't wake light sleepers, but it's your best chance at keeping the peace when grinding coffee whilst others still slumber.
The GX420851 was one of the better performers in our grind consistency testing, and is likely to please the vast majority of coffee drinkers.
When we put pourover grinds from the GX420851 into a series of sieve shakers, more than half of the grinds fell into the ideal size range. Only 14% of those grinds could be classified as much too small or large (these overly fine and coarse particles are the ones that can really mess up the extraction of the coffee's flavor). This relatively tight distribution of grind sizes made the GX420851 one of the top performers in this test.
That consistency carried over to our real-world pourover test. One would expect a consistent grinder to create the same extraction time (time from the water hitting the grinds to making it all the way through the filter) everytime you make a cup of pourover coffee. When we made multiple cups of pourover coffee with the GX420851 the extraction times varied by only 3 seconds. This was one of the best performances we observed in this test.
Unfortunately the GX420851's consistency does fall apart a bit at the finest and coarsest ends of the spectrum. On the fine end, we found this machine unable to create grinds worthy of use in an espresso machine (which isn't uncommon in countertop grinders). More importantly, when grinding at a coarse French press setting, the GX420851 tends to create more fine coffee dust than it does when making pourover-sized grinds. This doesn't mean you shouldn't make French press coffee with the GX420851, but the results likely won't be as good as when making a pourover.
This machine also struggles a bit more than most in creating the same amount of grinds each time. When we weighed the results of multiple rounds of grinding we found a 2.5 gram discrepancy between doses. This difference is small enough that most people probably won't notice when the grinder shortchanges them a bit, but those with more discerning palettes may be a bit disappointed by the occasional weak brew.
The GX420851 makes enough of a mess that a damp rag is a required accessory, but not so much that the cleanup feels overly arduous.
The GX420851 keeps things relatively tidy during the grinding process, with pretty much all of the coffee ending up where it's supposed to be in the grinding cup. However, that cup builds up so much static while the burrs are spinning that an almost impossible amount of grinds cling to the wall of the container. That makes getting all of the grinds out without spilling at least some onto the counter a near impossibility.
The GX420851 uses a scale to measure the grounds, which can be useful as many coffee makers will suggest their dosage by weight. We found that it was easy to tare that scale, so even if you're not using the provided grind cup you can get an accurate measurement.
A large grind collar lets you select our desired grind size, and plus/minus buttons allow you to select the desired amount of coffee (in grams, ounces, or cups). Then just press a button to start grinding, and you're good to go. This process is relatively seamless and straightforward.
The only downside to this interface is that the grind size is the only setting the machine can "remember" as it is set with an analog dial. The grind amount, and whether you'd like to select it in grams, ounces, or cups, must be re-selected every time you use the machine.
Dismantling the machine for cleaning is relatively easy, and the included brushes are stiff enough to get the burrs clean, but soft enough that you don't feel like you're going to scratch the stainless steel construction.
This is where the GX420851 really shines. It somehow manages to emit only an 83.6 decibel, low hum when in use. That results in a low-pitched, relatively inoffensive murmur that might not even be noticed in the next room.
The GX420851's price tends to fluctuate a bit online, but even the highest prices we've seen feel quite fair given its good grind consistency and impressively low volume. It certainly isn't a bargain-basement machine, but you do get quite a bit for what you spend.
The KRUPS GX420851 grinds well while keeping the noise to a minimum. If quietness is at the top of your grinder checklist, this machine delivers without sacrificing grind quality.
— Max Mutter and Michelle Powell