What is Grind-by-Sync? Espresso machines and grinders for home use that communicate with each other. The grinder-machine combination detects when the espresso is running too fast or too slow and adjusts the grinder accordingly. After 15 years of experience in the restaurant industry, this technology is now making its way into our homes. But let's be honest: Do we really need this? Does the system work at home when we only brew a few espressos a day? Which machines and grinders have the potential to quickly and reliably brew great espresso?
Or is this all just marketing hype to lure coffee drinkers from fully automatic machines to portafilter machines without really convincing them on quality?
In this blog post, I'll examine the technology, evaluate it critically, and provide manufacturers with a specification of what I expect from a well-functioning espresso grinder-and-machine combination. And let me be clear about one thing: If a grinder uses 100 grams of coffee to dial in an espresso, your system doesn't work!
The Promise: Never Adjust Grind Size Again
"Wonderful, synchronization!", you might say. But it's not that simple. There are incredibly many pitfalls that we encountered when rolling out synchronization between grinders and espresso machines in restaurant practice. The technology promises to automatically compensate for fluctuations caused by bean aging, moisture, or variety changes and to bring extraction "on target". But how much coffee is needed to dial in the grinder? Who at home actually makes enough coffee to give the grinder the necessary data and references to adjust? And don't I still have to set the grinder's base setting manually myself?
How It Works – Theoretically
The espresso machine measures key parameters during extraction – flow rate, 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. Flow measurement is limited on many machines to total volume, not 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, which enable better synchronization and extraction control.
What the Grinder Needs:
- Grind-by-Weight function (absolutely essential!)
- Electronically adjustable grind size
- Low retention!
- Communication interface to the machine (serial, WLAN, Bluetooth)
What the Machine Needs:
- Precise volumetrics (without good volumetrics, false signals go to the grinder)
- Stable extraction parameters (pressure, temperature, flow)
- Ideally: sensors for flow rate and flow/pressure control
Why Grind-by-Weight is Essential
Without Grind-by-Weight, the system doesn't work properly. Why? When the grinder adjusts the grind size, the output amount of coffee also changes with time-based grinders. If it grinds finer, less coffee comes out. This distorts the brew ratio, and extraction goes completely off the rails. You're adjusting two parameters simultaneously – a no-go for reproducible results.
Electronic grind size adjustment is of course also a prerequisite – but that goes without saying. Low retention is also a central requirement. Because proper verification of adjustment only works if we actually see the "new grind size" in the portafilter on the next shot and not still some grams of the old grind.
Current Systems at a Glance
Mahlkönig Xenia & E64 WS Home – The German Precision Approach
With the acquisition of Xenia, Mahlkönig brought not just a machine, but an entire platform into its portfolio. The Xenia remains technically an independent system with thoughtful details: two stainless steel boilers, actively heated brew group, and it's relatively quick to get ready. Additionally, it's capable of controlling pressure profiles.
The E64 WS Home ("Weight & Sync") brings Grind-by-Weight from Mahlkönig for under 1,000 euros to the home market for the first time. The system is called "Grind-by-Sync" here: The Xenia measures during extraction 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 from November. Xenia production starts in December, delivery end of December/early January.
Quick Mill & Eureka Tio – The Italian Surprise
A cooperation we didn't expect: Quick Mill and Eureka present with the Tio a cooperative system. Quick Mill cleverly redesigned the machine (1.4-liter steam boiler, thermoblock for the brew group): Instead of the previous system with its own bayonet, there's now a classic dual bayonet. Finally, commercially available portafilters can be used – this makes the machine much 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 provides feedback. The system works with a "2–3 second rule": If extraction stays outside the target range three times for two to three seconds, the grinder adjusts the grind size.
Price: Approximately 2,600 euros for the machine and 800 euros for the grinder. Market Launch: Q1 2026
The Other Players
Nunc: Technically probably the most mature. Bidirectional communication, large data storage with previous extractions, presumably capable of learning with AI support. Plus: "nunc." beans can be used, which the machine naturally knows. This makes base adjustment easier. Machine production reportedly started, but delivery continues to lag.
Sage/Breville Oracle Dual Boiler: The pioneer with integrated grinder. Responds with a delay and adjusts finer or coarser when the coffee is significantly outside the range.
Rocket: Already uses the technology on the restaurant machine with Bentwood. Likely coming soon in combination with a volumetric machine like the Bicoca and the new home grinder.
Datum Coffee takes the most open approach: no proprietary beans, no exclusive partners, platform for all roasters — Kickstarter end of 2026.
The Reality Check: What 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 quickly adds up to 60 grams before the grinder even reacts. With a 250 g bag for 10–20 euros, that's frustrating. And then the grinder has to do the adjusting – but does it nail the next shot? If not, 80 grams are already gone.
The Difference from Restaurant Use
In restaurants, we pull one espresso after another. The grinder adjusts gently throughout the day. It has a base setting, and if high humidity causes extraction times to lengthen, it's carefully readjusted.
At home? When do we actually pull multiple shots in a row? And how precisely does the system then adjust? How capable is it of making a sufficiently strong grind size adjustment? And what about grinders with retention? Does the old coffee still in the grinding chamber from the last shot in the old grind size get ground out?
The Technology Only Works with Regular Use
This technology simply doesn't work if you "make three shots over three days". If you really leave the beans in the hopper for three days, none of those shots will be consistently in range because you'll have to gently readjust the grinder anyway.
Base Adjustment Remains Manual Work
At this point, I assume you'll have to do the base adjustment of all grinder-machine combinations yourself. I'm happy to be corrected. If shots are then regularly pulled – yes, then the synchronized espresso grinder-machine combination plays to its strengths.
For Whom Does It Really Make Sense?
Sensible Use Cases:
- Households with multiple coffee drinkers – one sets it up, the others benefit
- Offices and shared apartments – many shots, consistent quality
Less Sensible For:
- Beginners – you still have to learn the base adjustment
- Occasional drinkers – too few shots for meaningful adjustment
- Purists – those who see the adjustment process as part of the ritual
The Test Protocol: How We'll Test These 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 until target range?
- The Daily Routine: One shot each in the morning, afternoon, and evening over several days
- The Consistency: How cleanly does the system maintain extraction under changing conditions like humidity or dry air (keyword: static charge)?
Flow Profile Instead of Just Grind Size
The real potential lies in the interplay 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 adjust the grind size next time", but can react at the moment when the shot is running.
Shot running too fast? The machine reduces the flow or pressure to still bring the extraction into the target corridor. On the Maro, this function is called "Smart Profiler".
Let's assume the perfect grind size gives us 100% extraction potential. With flow adjustment during the shot, we might get to 75% – still significantly better than a ruined shot. When a shot is bound to fail, one that shouldn't fail, so obviously channeling, too coarse a grind and everything sprays, the coffee is down the drain. With flow control, it looks better – and tastes better.
Conclusion: Evolution, Not Revolution
Grind-by-Sync is a logical further development, but not a silver bullet. The technology can help, but will likely not initially free anyone from manual adjustment. In households with many coffee drinkers or in the office, it makes sense. For the ambitious home barista who celebrates his morning espresso? Not really.
What we would wish for: open standards. If Eureka or Mahlkönig would open their interfaces, all machines could benefit and Roxy, Maro, Meticulous and Co. could simply connect. These machines seem made for communicating with a grinder.
The technology is there, it works – in restaurants for 15 years more or less. Whether it conquers the home market depends on whether manufacturers understand that three wasted shots in the morning doesn't make anyone happy. We'll keep an eye on it and test as soon as devices are available.
We're excited to see what manufacturers will deliver next year. For now, we remain as always curious and open – but also a bit the skeptical party poopers from Basel.
Your Benjamin Hohlmann
