Femobook A4Z & A5 Review: A Tale of Two Grinders

When I first heard about battery-operated grinders, I have to admit I was skeptical.

The idea felt stuck somewhere in between: not as portable and satisfying as manual grinders, yet not as quick and powerful as traditional electric ones. But after several months of using the Femobook A4Z, I realized that I had initially misunderstood the concept. This type of grinder has some merit – even in the crowded market today.

Since the A4Z and A5 grinders share the same core design, I decided to review them together in a single post. This also gives me the chance to highlight both their similarities and differences. After all, just because one of them is excellent, it doesn’t automatically mean the other delivers the same experience.

Actually, this review is long, long overdue. I have been planning to share my full thoughts on the A4Z for a while.

I have had this grinder since September 2024 and also featured it in my “best of 2024 video” as one of the honorable mentions that almost made it to the top 5 list.

I had then planned to do another deep dive on the A4Z as part of my round-up of the best pour over grinders. That project was scheduled for early 2025, but has now been delayed for months due to complexities and new products that keep appearing (and maybe also a bit of procrastination from my side – it is daunting to make a list like that).

Meanwhile, there’s been growing chatter in coffee communities about just how good the A4Z actually is. So rather than leave people wondering, I wanted to provide this earlier update (Spoiler alert: I agree with a lot of the online sentiments)

👉 Check current price here: A4Z | A5

Heads up: If you want to jump directly to my flavor evaluation of the A4Z, then click here

Disclaimer: Both review units were provided by the brand. As always, opinions are 100% my own.

The Femobook Story

In 2022, a new grinder brand appeared seemingly out of nowhere, launching with a remarkable first product: a unique looking 68mm conical grinder that immediately caught the attention of coffee geeks worldwide. The Femobook A68 offered a premium build quality, magnetic connections throughout, and innovative approaches like completely tool-free disassembly.

The name itself raised eyebrows, sounding more like a questionable laptop brand than premium coffee equipment, but it actually carries meaning in Mandarin Chinese, where “Femobook” apparently sounds like “must grind.” 1Zpresso also uses a similar phonetic pun, where “1Z” in Chinese is pronounced like “easy.”

Besides the name and origin in Taipei, the capital of Taiwan, Femobook shares significant overlap with 1Zpresso, including design elements and even personnel.

For the record, I did visit Femobook’s showroom in Taipei while I was there to shoot a video with former Coffee World Champion, Sherry Hsu.

I also tried to do a bit of detective work to see if there were any clear links between Femobook and 1Zpresso. The staff was open about the fact that the two companies have a friendly relationship and that the owners know each other well. I tried to dig a bit deeper, but that’s as far as I got.

So, is Femobook a sister brand or somehow part of 1Zpresso? I honestly still don’t know. But to me, what matters is how the grinders perform.

Besides, in the coffee world, these kinds of quiet partnerships aren’t exactly rare. For example, Mahlkönig, Ditting, and Anfim are all part of the Hemro Group. Breville owns both Baratza and Lelit. And many of the classic Italian brands share a lot of design elements because they fall under the same corporate umbrella. So, if Femobook and 1Zpresso are connected somehow, it’s probably not a big deal.

The Battery-Operated Evolution

Femobook’s first grinder, the A68, was a heavy and imposing machine that needed an external power brick, kind of like those older laptop chargers. But recently, the company has made a shift toward battery-powered models.

They’re not the only ones doing this either. The market for battery-operated grinders is starting to grow quietly, as more brands begin to explore that middle ground that is essentially electrified hand grinders.

The good thing about battery operated grinders is that they offer some of the same benefits as manual ones: Little to no retention, quiet operation, low RPM’s, and of course being much smaller than traditional electric models. Unlike traditional grinders, manual ones don’t have a chute. This fixes so many inherent problems that have traditionally plagued electric grinders. Less worries about clumping, regrinding, retention, and heat generation.

What makes the A5 and A4Z unique is that they’re essentially identical grinders with one crucial difference: their burr sets. The A5 houses 53mm heptagonal burrs capable of handling both filter and espresso brewing, while the A4Z features 48mm conical burrs that share the same geometry as the beloved 1Zpresso ZP6. This means it’s strictly for filter – it can’t grind for espresso (trust me, I’ve tried).

Design and Build Quality

The design language of the Femobook grinders reminds me right away of high-end manual grinders, especially the 1Zpresso K series. Visually, it feels like one of those grinders merged with a motor and a stand. The result is something both familiar and new.

Both the A5 and A4Z are built entirely from aluminum alloy, which gives them a sturdy and elegant look. Magnetic components are used in key places: the catch cup, bean funnel, and the small brush under the cone-burr.

The hopper fits up to 55 grams of beans, which is more than enough for most home brews. However, the catch cup only holds around 30 grams, so we’re clearly in the single-dose range. These models are aimed at today’s modern single-dose drinker, not someone brewing full pots the old-fashioned way.

Both grinders share an 8-micron per click adjustment system.

It works pretty well for the A5, where the precision proves valuable for espresso dialing. However, it can be a bit difficult to track settings since there are so many steps and revolutions to keep track of.

There are almost two full revolutions between espresso and pour over setting for the A5, which can feel overwhelming.

The A4Z could probably benefit from a more conventional grinding range with fewer clicks, making it easier to track settings for filter brewing. Super fine adjustments aren’t really needed for the typical French press, AeroPress and pour over brewing of the A4Z.

On the other hand, you’ll probably be able to get all your grindings need covered within a relatively narrow band, so you won’t need to count revolutions like you would with the A5.

Still – it feels a bit lazy to equip the A4Z with the exact same adustment range as the A5. For example: I grind on setting 2.5 for my typical Hario Switch technique. However, for a slightly coarser V60 I might grind at setting 3.5-4. So there’s about 10-15 clicks in between. Generally, you’ll probably be moving minimum 5 clicks each time you want to make a meaningful adjustment.

In daily use

At first, I thought adding a battery to a grinder was unnecessary. But after using the A4Z for nine months, I’ve realized that it’s a quite nifty little thing to live with. Granted, hand grinding is not a lot of work, but we’re all lazy in some ways.

During my nine months with the grinder, I’ve only charged it three times. And that’s with not quite daily use, but still frequent use, plus occasional extensive testing sessions where I have been grinding multiple rounds. If you’re only grinding for pour over, the battery lasts so long it almost feels unreal.

For everyday coffee brewing, having a battery-powered grinder is surprisingly liberating. There’s no power cord to manage, so you’re not restricted to one specific place on the counter. You also keep a power outlet free for something more essential, like your toaster or blender.

Both the A4Z and A5 models use USB-C for charging. You can charge them with your regular phone charger or even a power bank.

The rechargeable batteries they rely on are of the standard type and can easily be replaced by the user if they get worn out in the future.

However, when we’re talking espresso and the A5, things get a bit more demanding. Grinding fine espresso grounds takes more time and energy, so the motor has to work harder and the battery drains more quickly.

I haven’t done enough espresso grinding myself to find the capacity limit of the battery, mostly because I didn’t want to use up so much coffee just for testing purposes.

But according to detailed tests from my colleague from Our Coffee Shelter, a full battery gives you about 27 to 28 espresso shots, which is in line with what the brand states. That’s a significant drop compared to the 125 or more filter brews you can expect from one charge.

In my initial review of the A5 on YouTube I remarked that nobody will probably see this as a travel grinder, since it would take up a significant allocation of your carry-on quota with most airlines. But the grinders do come with a nice travel case, so for example, a pop-up brew bar at a farmer’s market, or a cupping session out in town. In those instances, it would be convenient enough to bring along. So portable, yes. Travel friendly? Not exactly.

Performance and Grinding Speed

Before talking about grinding speed and performance, I want to mention something that might stand out right away: these grinders are not the fastest. Compared to most electric grinders, and even many manual ones, the A5 and A4Z are on the slower side. But in real daily use, that slower speed doesn’t feel like a major problem – especially if you’re making pour over coffee.

A typical pour over dose of 20 g will take 45 seconds to grind – and then the grinder will continue to run for 5 seconds before the auto shut-off feature kicks in. So that’s 52 seconds of grinding action in total.

But, while the grinder is chugging along, you still need to take care of the rest of your setup. Heating water usually takes longer than 50 seconds anyway, so it’s not a big deal.

During that time, you’re also folding and rinsing your filter, warming up your brewer, and getting everything into place. So the slower grinding becomes part of a calm and intentional brewing process.

Important: One thing to be aware of is that unlike my review unit from 2024, newer versions have moved away from the auto shut-off feature, and instead run a timed cycle. This is a small step backwards, since it will drain more battery unless you turn it off.

The slow grinding speed does have a technical benefit, though. Lower RPMs tend to generate less heat and create less friction inside the grinder. Beans move a long in predictable pattern without overloading the grinding chamber. This helps with a more even particle distribution and can lead to more clarity in the final cup. I’ve noticed this clearly over the last few years as I’ve tested more grinders that allow for RPM adjustments.

Both Femobook grinders operate at about 60 RPM. That’s significantly slower than most electric grinders and even below the average speed of a manual one. Of course this depends on the user, but I’d estimate my hand cranking speed is probably closer to 90 RPM.

When it comes to espresso, the story changes a bit. Grinding at such a fine level, the slower speed and longer grind time can start to feel like a disadvantage. This is especially noticeable if you’re used to a fast electric grinder in your morning routine.

For example, grinding a 16-gram dose will usually take between 55 and 75 seconds.

So while the gentle, steady grind can feel relaxing and precise when brewing pour over, it may turn into annoyance with espresso – depending on your habits and what you expect from your grinder.

Sound Performance

The sound performance of both grinders is great. When running without beans, the A5 produces about 62 dB, and when loaded, it reaches 75 dB. The A4Z is slightly quieter in both cases, usually 2 to 3 dB less. This small difference probably comes from some changes in the internal gears, since the two models I own were made about one year apart.

Femobook has made similar improvements before, such as with the A68, where the company worked to reduce noise in newer batches.

Still, the decibel number is only part of the story. In daily use, both grinders are among the quietest electric models I’ve tried. The sound they make is a soft and steady rumble. It’s not sharp or annoying, and there is no high-pitched noise like some cheaper grinders have. This makes a difference, especially in the early morning when someone else might still be sleeping in your house. It’s very possible to grind coffee without waking up everybody.

The tone of the sound is smooth and gentle, so it feels more natural, almost like part of the kitchen environment. Because of this, I think these grinders are among the most quiet electrical ones.

There is only one downside: grinding takes longer compared to the 10-25 seconds from a standard electrical grinder. So while the peak volume is lower, it continues for longer.

Grind Quality and Flavor Profiles

Femobook A4Z: Taste and Performance

When I got the A4Z last year, I expected it to perform pretty similarly to the 1Zpresso ZP6. They share the same general burr geometry, and I assumed the big difference would just be the convenience of the A4Z’s motor.

But the more I used it, the more it started showing me it wasn’t just a motorized ZP6: it was something else entirely.

One moment that really stuck out was when I brewed a cup of a Rwandan Musasa Ruli washed Red Bourbon I had roasted at home on the Bullet.

Nothing fancy, just a regular roast. I brewed it with the Fellow Aiden with my standard light roast profile, but the result was one of those rare, jaw-dropping cups that stays with you for weeks or even months. It was so clear, so intense that it made me stop and wonder what was going on. That kind of cup where you double-check your water, your recipe, even your sanity, because it just doesn’t seem like it should taste that good.

That’s when it really hit me: maybe the A4Z isn’t just a ZP6 with a motor.

From that point on, I started testing the A4Z more seriously, especially while working on my electric pour over grinder comparison video (as mentioned this is a project I’ve been working on for way too long now).

I kept putting the A4Z up against top-tier flat burr grinders like the DF64V with SSP Brew burrs, Eureka Single Dose Pro with AP burrs, and the Fellow Ode. And every time, it held its ground.

That’s something the ZP6, great as it is, was never able to do in my testing.

What’s remarkable is that the A4Z delivers the kind of clarity and precision you expect from those premium flat burr setups, but with the sweetness, body, and ease-of-use that conical burrs are known for.

It manages to surpass the already excellent ZP6 by offering a bigger body, better sweetness, and more balanced coverage across the palate. Where the ZP6 tends to narrow its focus on a specific flavor band, the A4Z delivers a wider, more immersive cup with a full mouthfeel and a more developed aftertaste, while still retaining what makes the ZP6 great.

During blind testing sessions, both my testing buddy and I consistently chose the A4Z when pitted up against the ZP6. I thought it would be closer in terms of cup-quality, but I think even inexperienced tasters with a smaller frame of reference would notice the difference. I will say the cups are about 80% similar, but it’s like the EQ is just tweaked up a notch in the most important areas when it comes to the A4Z.

The aftertaste of the ZP6 stayed more toward the front of the tongue and didn’t have the same lingering sweetness or complexity. There were a few moments, particularly with very floral Ethiopians, where the ZP6 brought something interesting to the table, maybe a touch more tea-like character, but even then, we still preferred the A4Z. It just had a bit more of everything.

In four blind taste tests that were double-checked for extraction yield and drawdown time, the A4Z was the winner.

I originally thought maybe it was just the precise RPM of the motor giving it an edge, but after taking the grinders apart and looking more closely, it turns out the burr design itself is subtly different too.

I’m sure that Fembook believes that this burr set is 100% identical to the ZP6. So what could the explanation be?

My ZP6 version is from the very first batch. So it’s possible that 1Zpresso has made slight modifications without telling anyone, and that a newer generation of ZP6 grinders is equipped with a slightly different burr design. That certainly wouldn’t be the first time in history. (Think back to K Max –> K Ultra & X Pro –> X Ultra).

But whether it’s the same burr set or not, there’s also the steady RPM factor that might play a role.

Are the burrs identical or slightly different? I have tried to add enough photos, so that you can hopefully make your own opinion on the matter. (ZP6 to the right)

A4z vs Timemore 078

Now, given all my positive descriptions of the A4Z’s flavor profile, I know what you are going to ask next, and that is: how does it compare to the Timemore 078?

To answer this properly, I set up several side-by-side tests. The first comparison used two Hario Switch brewers and a Colombian honey-processed coffee from Aponte, roasted by the Danish roaster Prolog.

Right away, I noticed something was off: the drawdown time for the 078 was slower. And sure enough, in the cup, the 078 tasted slightly bitter, while the A4Z offered a more balanced and enjoyable profile. TDS measurements confirmed this difference – the 078 was about 0.07 higher. I decided not to draw conclusions from this flawed test and moved on.

For the second round, I used a different coffee to avoid palate fatigue. This time a washed Peruvian coffee from the same roaster. However, this time the A4Z produced a slightly higher TDS – around 0.02 to 0.03.

While not a perfect match, it was enough to compare meaningfully. Again, the A4Z stood out. The cup was juicier, with more lively acidity and a more engaging overall character.

To eliminate any remaining variables, I ran a third test. I went back to the Aponte coffee and fine-tuned the A4Z using its precise 8-micron adjustment steps. This let me match TDS levels exactly between the two grinders. For this final round, I also did a blind test, using two samples from each grinder.

I was able to match and identify both A4Z cups. They had more clarity, stronger acidity, and more fruit in the aftertaste. The 078, by comparison, felt more neutral. It was still a good cup, but next to the A4Z it came across as less exciting.

What I saw in these tests matches my daily experience. As part of my so-called “content creator” lifestyle, I regularly test new grinders. On average, I get one or two every month. Currently I have around 45 in my apartment and dozens of burr sets to allow even more permutations.

And yet, the A4Z has managed to stay on my main brewing station for a surprisingly long time. Granted, part of this is due to its cordless and compact nature.

The Timemore 078, on the other hand, is located in my kitchen but not on my main station. And not permanently plugged in. I’ve had it for over two years now. I use it when I want contrast – when I want to look at a coffee from a different perspective. But it’s not my first choice for everyday brewing.

To me, this unconscious usage pattern says a bit about both my preferences, and the capabilities of the grinders. The 078 is often described as a unicorn grinder in the coffee community. And yes, with certain beans it can be excellent. It’s also highly consistent. But in my experience, it often delivers a harmonious, yet static cup.

That connects to something I’ve written about before: the idea of a “cup journey.”

A really great cup of coffee usually develops over time. You might get a sharp, bright note at first, then something smoother and richer in the middle, and finally a change in the finish – maybe something floral or fruity. The 078 often gives a strong first impression, but the rest of the cup stays in that same space. It doesn’t move much.

The A4Z, in contrast, has more evolution. Like the 078 (and most other conicals), it delivers a higher average of good brews compared to high clarity flat burrs, but its flavor profile aligns better with what I personally enjoy: clarity with complexity.

One interesting lens to view this through is the Bouba-Kiki effect.

Yes, the name might sound like a kid’s cartoon, but it’s actually used in legitimate sensory science, especially in food studies, to describe how we associate shape and texture with taste.

The Bouba-Kiki framework comes from two abstract shapes: one soft and rounded (Bouba) and one sharp and spiky (Kiki).

Across different languages and cultures, people associate the rounded shape with soft, mellow qualities, and the sharp one with bright or intense ones. This can apply surprisingly well to coffee and grinders.

In this model, the 078 is clearly a Bouba grinder. It produces clean, elegant, and harmonious brews. The A4Z leans more toward the Kiki side – not all the way, like the SSP multipurpose burrs, but closer. It brings more edge, more brightness, and a bit more tension to the cup.

Of course, taste is personal. You might prefer Bouba-style grinders and the calm, balanced cups they produce. But I enjoy a bit of Kiki energy in my coffee – a kind of sparkle or angularity that keeps things interesting.

This framework has helped me understand and describe my preferences. In fact, most grinders I’ve tested could be placed somewhere along this axis. And I think other coffee geeks might find this model mentally stimulating.

Here’s how I see the Bouba-Kiki characteristics breaking down in the world of grinders/burrs.

Kiki (Jagged/Spiky)

• Bright acidity
• Complexity
• Astringency
• Clarity
• Aftertaste/Echo

Bouba (Round/Smooth)

• Balanced acidity
• Harmony
• Creamy body
• Juiciness
• Smooth lingering finish

A5 Heptagonal Performance: Excellent but Expensive

Now, let’s look at the twin brother, the A5. As the name indicates, this grinder uses bigger 53mm heptagonal burrs.

However, the results are pretty much what you’d expect from this 7-spoke style geometry.

In side-by-side comparisons with other heptagonal burr grinders like the 1Zpresso K-Ultra, the differences are there, but they’re subtle. The A5 delivers cups with that familiar vibrancy and clarity often associated with heptagonal burrs. The K-Ultra might have a slight edge in overall refinement, especially for filter brews, but the A5 is not far behind.

In fact, the A5 does a great job when it comes to extracting bright, well-defined flavors. It emphasizes a snappy, aggressive acidity while still maintaining a respectable amount of body. If you enjoy those crisp, high-acid notes – think green apples or tart berries – you’ll likely appreciate what this grinder can do.

That said, the larger burr size doesn’t seem to bring many unique benefits in terms of flavor. It might help a bit with grinding speed, but not in a way that feels game-changing. The flavor reminds me of 1Zpresso’s X-Pro – a grinder that had a loyal following before it was strangely discontinued. The profile is very similar: clean, acidity-forward, and focused.

When it comes to espresso, the A5’s slower grind speed becomes more noticeable. A typical double shot takes somewhere between 50 seconds to 1 minute and 10 seconds, depending on your roast and machine. That’s on the slow side, and not everyone will be okay with that during a busy morning.

Still, the espresso quality is quite pleasant. It’s lively, high in clarity, and detailed. But it doesn’t deliver a full, rich mouthfeel across the whole palate. This is common with heptagonal burrs: they’re better at brightness and complexity than depth or heaviness. So you won’t get those creamy chocolate notes or syrupy textures that are often preferred for darker roasts.

This fits a broader pattern I’ve noticed in many grinders. If a burr set performs with high clarity for pour over, it usually offers similar results for espresso – unless there’s a big change in how the grinder operates, like adjusting the RPM. If the A5 could run at a higher speed, say between 150 and 300 RPM, I think the espresso shots would likely gain more sweetness and a rounder profile.

So yes, the A5 can make good espresso, but it has a distinct personality. It suits light and medium roasts and people who value complexity over body. If you like espresso bold, round, textured, and creamy, then this grinder may not be your ideal match. On the Bouba-Kiki scale, the espresso leans very “Kiki”.

The Value Question

When it comes to price, this is where the A5 stumbles. While it performs well independently, similar heptagonal burr experiences are available much cheaper. Femobook’s own A2 delivers comparable flavor at a fraction of the price. The Outin Fino offers battery power and similar geometry for less than half the cost. In spite of its smaller burr set, the flavor quality is similar.

Manual alternatives like the Kingrinder K6, 1Zpresso Q2, and K-Ultra match the A5’s performance while being more portable and often faster. The convenience of electric grinding fades when you factor in the A5’s frequent charging needs for espresso use.

Two Grinders, Different Destinies

After months of daily use, I’ve come to a sort of conclusion – that might feel a bit unfair: These grinders share identical bodies and motors, yet one component pushes them into entirely different market territories.

The A5’s dual-purpose burrs thrust it into a crowded, competitive space where battery-powered grinders face their greatest challenges. Making quality espresso demands speed and power, difficult achievements with limited battery capacity. Against competitors like the faster, cheaper DF54 running at 1400 rpm, the A5 struggles to justify its premium.

The A4Z can look into a different destiny. Its filter-focused burrs liberate it from espresso’s demanding requirements, and places it in a specialized niche with less competition.

When it comes to crystal-clear filter coffee from a compact, battery-powered platform that works great out of the box, the A4Z stands in a unique spot. And when you consider it next to so-called titans and “end-game grinders”, it’s not only tiny, it also has a relatively affordable price point.

You don’t have to swap burrs, mess with alignment, or go through all that geeky trial and error. You just get a grinder that performs at a high level in a quiet, compact, cordless form factor.

That simplicity combined with serious performance makes the A4Z a standout, especially for people who want high-end filter coffee without the UX complexity.

That said, this is definitely a specialty/light-focused grinder. It really shines with roasts from the likes of Coffee Collective, Manhattan, Pala, or Noma. It doesn’t do quite as well with traditional chocolate and nutty medium roasts, where many flat burr grinders in that medium price range would be better picks.

But for modern, high-clarity coffees, there’s no doubt that it’s the best conical grinder I have tried, and that it will beat many flat burrs, too.

potential for improvement

As much as I’ve come to appreciate the Femobook grinders, there’s still room for improvement .

• Modularity: The most noticeable missed opportunity, is the lack of modular burrs. If Femobook had designed this model to support interchangeable burr modules, especially something more suited for espresso (like a J-Ultra style module), it would open up a ton of possibilities. It only takes few seconds to click the burr module in and out, so this would have been a cool way to utilize the frame/body for more things.
• Handle compatibility: Another thing I kept wishing for was a removable handle. Since the A4Z is so compact and the grinding chamber is so easy to remove, it seems like it should be ideal for travel. With a dedicated handle for manual use, it could work as a true hybrid grinder. A simple addition here would really push the design closer to something both practical and versatile.
• RPM Control: Finally, it would have been cool to see RPM control. More and more grinders have it nowadays, and these are not cheap products. I keep thinking what would happen if the A4Z’s burr set were spinning at a 350 RPM range. Maybe they would be espresso capable? After all, these burrs are also inspired by the similar looking Etzinger M2-burrs which offer a solid espresso performance. And A5 would probably also benefit from grinding espresso at higher RPM’s.