What is Grind-by-Sync? Espresso machines and grinders for the home that communicate with each other. The grinder-machine combo detects that the espresso is running too fast or too slow and adjusts the grinder accordingly. After 15 years of experience in the catering industry, this technology is now making its way into our homes. But honestly: Do we really need this? Does the system actually work at home when we only brew a few espressos a day? Which machines and grinders have the potential to brew espresso quickly and well?
Or is this whole thing just a marketing hype to lure coffee drinkers away from fully automatic machines to portafilter machines without really being convincing in terms of quality?
In this blog post, I will shed light on the technology, provide a critical assessment, and give manufacturers a checklist of what I expect from a well-functioning espresso grinder and machine combination. And let one thing be clearly said here: If a grinder uses 100 grams to dial in an espresso, then your system is not working!
The Promise: Never adjust grind size again
“Wonderful, synchronization!”, one might say. But it’s not that simple. There are an incredible number of pitfalls that we experienced in gastro practice when rolling out synchronization between grinders and espresso machines. The technology promises to automatically compensate for fluctuations caused by bean aging, humidity, or changing bean varieties and to “get the extraction on target.” But how much coffee is needed to adjust the grinder? Who at home even makes enough coffee to provide the grinder with the necessary data and shots to adjust? And don't I still always have to set the grinder's basic setting myself?
How it works – theoretically
The espresso machine measures key parameters during the shot – flow, time, extraction behavior – and sends this data to the grinder. If the extraction deviates from the target values, the grinder automatically adjusts the grind size. For many machines, flow measurement is limited to total volume, not measuring milliliters per second.
The technical requirements for Grind-by-Sync to work
For synchronization between grinder and machine to work, both must meet certain requirements. I distinguish between basic requirements and ideal criteria that enable better synchronization and control of the shot.
What the grinder needs:
- Grind-by-Weight function (absolutely mandatory!)
- Electronically adjustable grind size
- Low retention!
- Communication interface to the machine (serial, Wi-Fi, Bluetooth)
What the machine needs:
- Precise volumetrics (without good volumetrics, there are false signals to the grinder)
- Stable extraction parameters (pressure, temperature, flow)
- Ideally: Sensors for flow and control of flow/pressure
Why Grind-by-Weight is essential
Without Grind-by-Weight, the system does not make sense. Why? If the grinder changes the grind size, the output quantity of the coffee also changes in time-controlled grinders. If you grind finer, less coffee comes out. This falsifies the brew ratio, and the extraction goes completely out of control. You are adjusting two parameters at the same time – a no-go for reproducible results.
An electronic grind adjustment is also a prerequisite, of course – but that goes without saying. Low retention is also a central requirement. Because a clean verification of the adjustment only works if we actually see the "new grind size" in the portafilter at the next shot and not still a few grams of the old grind.
Current systems at a glance
Mahlkönig Xenia & E64 WS Home – The German precision approach
Mahlkönig has not only brought a machine, but an entire platform into its portfolio with the acquisition of Xenia. The Xenia remains a technically independent system with well-thought-out details: two stainless steel boilers, actively heated brew group, and it is ready for operation relatively quickly. Furthermore, it is capable of controlling pressure profiles.
The E64 WS Home (“Weight & Sync”) brings Grind-by-Weight from Mahlkönig to the home market for the first time for under 1,000 euros. The system is called “Grind-by-Sync” here: The Xenia measures during the shot and sends the data to the grinder, which then automatically adjusts the grind size.
Price: Mahlkönig Xenia 2,999 euros for the machine, E64 WS 999 euros. Market launch: The E64 WS will be available at retailers starting in November. Xenia production starts in December, delivery at the end of December/early January.
Quick Mill & Eureka Tio – The Italian surprise
A collaboration we didn't see coming: Quick Mill and Eureka present the Tio, a collaborative system. The machine (1.4-liter steam boiler, thermoblock for the brew group) has been cleverly redesigned by Quick Mill: Instead of the previous system with its own bayonet, there is now a classic double bayonet. Finally, standard portafilters can be used – this makes the machine significantly more flexible in everyday use.
The Eureka grinder is based on the well-known Libra, but has been further developed: larger burrs, integrated scale, and smart technology that has been providing feedback for a long time. The system works with a “2–3 second rule”: If the extraction remains outside the target range three times for two to three seconds, the grinder adjusts the grind size.
Price: Approx. 2600 euros for the machine and 800 euros for the grinder. Market launch: Q1 2026
The other players
Nunc: Probably the most technologically mature. Bidirectional communication, large data memory with previous shots, presumably capable of learning with AI support. Plus: “nunc. beans” can be used, which the machine naturally knows. This makes the basic setup easier. Machine production has started according to the manufacturer, but deliveries remain sluggish.
Sage/Breville Oracle Dual Boiler: The pioneer with an integrated grinder. Reacts with a delay and adjusts finer or coarser when the coffee runs significantly outside the range.
Rocket: Already has the technology in use for the gastro machine with Bentwood. Probably soon in combination with a volumetric machine like the Bicoca and the new home grinder.
Datum Coffee pursues the most open approach: no proprietary beans, no exclusive partners, platform for all roasters. Kickstarter end of 2026.
The reality check: What the manufacturers don't tell you
The 60-gram problem
Let's do the math: Most systems only react after two to three failed shots. At 18–20 grams of coffee per shot, that's quickly 60 grams before the grinder even reacts. With a 250g bag for 10–20 euros, that's frustrating. And then it's the grinder's turn to adjust – but will it nail the next shot? If not, 80 grams are already gone.
The difference to the gastro sector
In the catering industry, we pull one espresso after another. The grinder adjusts itself gently throughout the day. It has a basic setting, and if extraction times increase due to high humidity, it is carefully readjusted.
At home? When do we actually pull several shots in a row? And how precisely does the system adjust then? How capable is it of making a sufficiently strong grind size adjustment? And what about grinders with retention? Is the old coffee, which is still lying in the chamber from the last shot with the old grind size, ground out?
The technology only works with regular use
This technology simply doesn't work if you “pull three shots in three days.” If you really leave the coffee in the bean hopper for three days, none of these shots will consistently be in the range, because you have to gently adjust the grinder anyway.
The basic setup remains manual work
At this point in time, I assume that you have to set the basic configuration of all grinder-machine combinations yourself. I'm happy to be proven wrong. If coffee is then pulled regularly – yes, then the synchronized espresso grinder-machine combination shows its strength.
Who is it really for?
Sensible usage scenarios:
- Households with several coffee drinkers – one person sets it up, the others benefit
- Offices and shared flats – many shots, constant quality
Less sensible for:
- Beginners – you still have to learn the basic setting
- Occasional drinkers – too few shots for sensible regulation
- Purists – who see the setup process as part of the ritual
The test protocol: How we will test the systems
- The extreme test: Adjust grind size completely (15 seconds flow time, target size 25 seconds)
- The measurement: How many shots / grams of coffee does the system need to reach the target range?
- Everyday life: One shot in the morning, at noon, and in the evening over several days
- The consistency: How cleanly does the system keep the extraction under changing conditions such as humidity or dry air (keyword: static charge)?
Flow profile instead of just grind size
The real potential lies in the interaction of good Grind-by-Weight grinders with very low retention and espresso machines with flow control. Classic espresso machines with static pump pressure can only influence the next grind and thus the next shot. Machines with flow control have a huge advantage: A Roxy, Maro, Decent, or even the Xenia can not only say “okay, we'll change the grind size next time,” but can react the moment the shot is running.
Shot running too fast? The machine reduces the flow or pressure to bring the extraction into the target corridor anyway. At Maro, this function is called “Smart Profiler.”
Let's assume the perfect grind size gives us 100% potential extraction. With flow adjustment during the shot, we might get to 75% – still much better than a ruined shot. If a shot blasts out that shouldn't blast out, i.e., obviously channeling, grind size too coarse and everything is spraying, then the coffee is ruined. With flow control, it looks better – and tastes better.
Conclusion: Evolution, not revolution
Grind-by-Sync is a logical further development, but no panacea. The technology can help, but will likely not free anyone from manual adjustment at first. It makes sense in households with many coffee drinkers or in the office. For the ambitious home barista who celebrates their morning espresso? Probably not.
What we would wish for: open standards. If Eureka or Mahlkönig would open their interfaces, all machines could benefit from this and Roxy, Maro, Meticulous, and Co. could simply dock on. These machines are made to communicate with a grinder.
The technology is there, it works – more or less for 15 years in the gastro sector. Whether it conquers the home market depends on whether the manufacturers understand that three wasted shots in the morning don't make anyone happy. We will stay on the case and test as soon as the devices are available.
We are curious to see what the manufacturers will deliver to us next year. For the moment, we remain as curious and open as ever – but also a little bit like the skeptical killjoys from Basel.
Yours, Benjamin Hohlmann
