Omix Plus Complete Guide
Part 1: The device
Omix Plus reads a single sample and hands back the numbers that decide how a green coffee should be roasted and how a roasted coffee should be dialed in: moisture, water activity, approximate true density, screen size, and a full color distribution, plus the room conditions the reading was taken in. Measurements that normally need three or four separate instruments come from one prepared sample. This half of the guide covers the hardware: the parts, how to calibrate, and how to take an accurate reading.
What’s in the box
Omix Main Unit
Sample Base
Green Bean Container (A)
Roasted Bean Container (B)
Ground Coffee Container (C)
Calibration Container (D)
Water Activity Calibration-Solution Bottle
Coffee Spoon
Scraper
Brush
Tray
Tempered-glass screen film
USB-C charging cable
Toolbox
Manual, warranty card, certificate, test report, and quick start guide
Know your Omix
Omix Plus comes apart into two halves. The Omix Main Unit is the top piece with the screen, the button, and the optics. The Sample Base is the bottom piece that holds the container, weighs it, and reads capacitance through the post in its center. The two click together over a magnetic connector, which is also how they charge.
Touchscreen - the 3.5-inch display on top of the main unit. Every result, menu, and calibration screen lives here.
Button - the single control on the top face. A short press powers on or triggers a measurement; a short press followed by a held press starts calibration; a hold powers off. Full gesture list is below.
Magnetic Connector - the contact point on the sample base. It carries power and data between the two halves, so the USB-C port on the side of the main unit charges both batteries at once, as long as the halves are clicked together.
Sample Base - the weighing and sensing platform. The center post is the capacitance electrode for moisture, and there is a scale underneath it for density, which is why the unit has to sit on a flat surface to read correctly.
The four containers
Four containers come in the box, marked A, B, C, and D. Which one you use is set by the sample and the measurement, and the shape of each container reflects that.
Green Bean Container (A) - Moisture, water activity, true density, bulk density, screen size, color, and environmental readings. Handles cherry, parchment, and roasted beans. The hole in the bottom drops over the sample base post to read capacitance for moisture.
Roasted Bean Container (B) - reads color on roasted whole beans, and doubles as the vessel that holds the saturated salt solution during water activity calibration. Instead of a hole, it has a post that pokes out, so it rests on top of the base post rather than reading through it. Moisture cannot be measured with this container.
Ground Coffee Container (C) - the shallow one, for reading ground color. Like B, it has a post on the bottom and sits on top of the base post.
Calibration Container (D) - the calibration vessel. Its top face is a color reference plate for Agtron calibration, and the underside carries the plate’s Agtron value. Each plate’s value is specific to that container, so if you ever swap in a different calibration container you have to set its value in CoffeeOS or on the device, or the color reading will be off.
The hole in Green Bean Container A drops over the base post so the post can measure moisture by capacitance.
Roasted Bean Container B carries a post on its underside and rests on top of the base post instead of reading through it.
Ground Coffee Container C works the same way as B, sitting on the post. It is the shallowest container.
The underside of Calibration Container D is printed with its plate’s Agtron value. Match this value in settings if you use a different plate.
The button
| Gesture | What it does |
|---|---|
| Short press (off) | Powers on. Release when the DiFluid splash appears. |
| Short press (on) | Triggers a measurement. |
| Short press, then hold | Starts calibration. The device detects which calibration you mean from what is in the sample base. Do it as a quick tap into a held press, not two separate presses. |
| Quick double-tap | Opens device information. |
| Hold | Powers off. Release when “Shutdown” appears. |
On the touchscreen. Swipe left to right on the READY screen to reach the menu (Measure, Calibrate, History, Settings). Swipe right to left to jump to your most recent result. From any subpage, swipe right to go back.
Keep it clean
Every reading depends on a clean, dry container and a clear sensor. Coffee dust, oil from roasted beans, and leftover grounds all shift results, and the closed chamber only helps if what is inside it is clean. Brush out the containers with the included brush between samples, and wipe the calibration plate before you use it. Fingerprints on the plate change the color it reflects.
Start it up
Place the empty Green Bean Container A into the sample base, set the main unit on top, and power on. The base needs to weigh and zero the container at startup. When it is ready the screen reads READY.
If the container is missing or has something in it, the device tells you before it will measure:
Container Abnormal - the base cannot find an empty Container A. Put one in and continue.
Container Not Cleared - there is coffee in the container. Empty it, then continue.
About “Initialize Container.” The third option on the Calibrate page will allow you to manually re-tare the container if you bypassed this step during startup. If you are only performing color tests, initializing the container can be bypassed safely. If you want to perform density readings, you can manually re-initialize in the Calibrate menu.
Calibration
Calibration standardizes each reading against a known reference. Run it about once a week, more often if you want tighter results, and any time readings look off. Omix Plus also prompts you when it senses a real change in ambient temperature and re-calibration is required.
Color (Agtron)
Color calibration references the reading against the plate on top of Calibration Container D. Place D in the sample base, set the main unit on top, then swipe left to right on READY, tap Calibration, and tap Agtron.
Place Calibration Container D in the sample base, plate side up, and set the main unit on top.
Swipe left to right on READY, tap Calibration, then tap Agtron. The device reads the plate and stores the reference.
Water activity
Water activity calibrates against saturated salt water. When water holds all the salt it possibly can, its water activity is a known, fixed value, so a saturated salt solution is a reliable reference to zero against. Prepare the solution well ahead of time so it is ready when you need it.
Using the bottle from the toolbox, add salt up to the lower line marked NaCl. Plain, non-iodized salt is best. Make sure it does not have silicon dioxide added.
Top it up with tap, RO, or distilled water to the upper WATER line. A funnel makes this much easier.
Cap the bottle, shake it well, and let it stand for an hour so the salt fully dissolves. You want undissolved salt still sitting in the bottom: that is your proof the water is fully saturated. If everything dissolved, you cannot be sure there was enough salt. Once mixed, the solution is reusable, so prepare it in advance rather than while you are trying to calibrate.
Pour the whole solution, undissolved salt and all, into Container B and set it smoothly into the sample base without tilting it.
Set the main unit on top and let it sit for two minutes. Then swipe to Calibration and tap Water Activity. The run takes 30 to 60 seconds.
A correct calibration lands near 0.753 Aw, in the 0.745 to 0.755 range. Pour the solution back into the bottle to reuse it, and rinse Container B.
Density (Initialize Container)
Density calibration is the same zero the device runs at startup: it weighs an empty, known Green Bean Container A as the baseline for every density and moisture reading. True density re-zeros itself every time you power on. If you ever start up without an empty Container A in place, run this again from Calibration, tap Initialize Container, before measuring density or moisture.
Prepare a sample
Sample prep is where density accuracy is won or lost. Omix Plus measures bulk density from the weight of the coffee and the volume of the container, so how consistently you pack that container is part of the measurement. Beans are not water; they do not fill every gap. Take fifteen beans out after a reading and the density changes. The goal every time is a container filled the same way, so the number is comparable to the last one.
Omix Bean Sweeper is an optional accessory, sold separately, not in the box. It gives the most repeatable fill, but it is a nice-to-have, not a requirement: the included Scraper does the job too. Get the Omix Bean Sweeper.
Set the bean sweeper on top of Container A, pour beans through it, and sweep. If beans cluster on the logo, push them off and in until everything has settled or fallen away. If gaps open up because beans dropped out early, add more on top and keep sweeping until there are no gaps and nothing is falling out. That is how you know the container is as evenly full as any other time.
No sweeper on hand? Fill the container past the rim and draw the included scraper flat across the top so the coffee sits perfectly level with the edge. The bean sweeper gives a more repeatable fill, but a carefully scraped sample works as well.
Why this matters. Because bulk density depends on packing and container shape, the same beans read differently on different meters with different sample prep methods. Omix Plus applies a fixed compensation factor so its bulk density lines up with MD500, a density meter already in wide use, which keeps your Omix numbers comparable to the readings and history people already have. Use a different meter and you may see a different value for the same coffee.
Take a reading
Drop the prepared container into the sample base and set the main unit on top. From here you can trigger everything with one press of the button, or open the measurement page and run moisture and density, water activity, or color on their own.
Place the filled container in the sample base. Moisture/Density in Container A; roasted whole beans in B; grounds in C.
Set the main unit on top so the chamber closes, then press the button. The closed chamber shields the sensors from ambient humidity, airflow, and your hands, all of which would move the reading.
Auto-detect or choose. Left on Auto Detect, Omix Plus identifies the sample from image, color, screen size, capacitance, and density all at once, then runs only the measurements that make sense for it. Green, parchment, and cherry skip color; roasted beans and grounds skip water activity. You can override the type in settings if you ever need to.
Environmental factors. A setting decides whether the device also logs room humidity, temperature, atmospheric pressure, and altitude alongside the coffee metrics. Those conditions affect the reading, so recording them makes a result easier to interpret later.
Water activity timing. Water activity takes roughly 30 seconds, so a setting lets it either run in parallel with the other readings or wait until you trigger it manually. Everything else finishes in about two to three seconds.
Reading the results
The first result page is the summary: sample type across the top, moisture and density together with the mesh range and volume per bean, water activity, roast level, and the room conditions along the bottom. Tap into any block for the detail behind it.
Moisture, density, and screen size
Tap the moisture and density block for the full breakdown. This is where true density, bulk density, the gap rate behind them, weight, screen size, and average bean diameter all live.
Bulk density - weight divided by container volume, adjusted by the compensation factor.
True density (Estimated Density) - the material density of the beans, with the air between them removed. Omix Plus photographs the packed surface, finds the gaps, the dark spaces and lines between beans, and calculates a gap rate. It subtracts that gap from the sample to estimate what the water displacement method would read. This is an estimate, not a perfect true density, but read next to bulk density it tells you the state the beans are in.
Why both numbers help - together they point to how to roast: how dense the beans are guides your charge temperature and how hard and fast to push the roast. Denser beans hold more heat and take more energy to develop.
Screen size and volume per bean - screen size is the range of bean sizes the device sees across the packed surface, read on the short axis; volume per bean is worked out from the full set of readings. Neither is a substitute for a physical sieve, but a validated screen size range will contain the sieve’s true value.
Water activity
Water activity is not moisture. Moisture is how much water is in the bean; water activity is how available that water is, which is what actually governs how a green coffee stores and stays stable. Omix Plus measures it with the chilled-mirror dew point method, the international reference approach, and reports the mirror and bean temperatures alongside the result.
How it reads so fast. The chilled-mirror method cools a mirror until dew forms, and the temperature at that moment gives the answer. Cool too fast and you overshoot the dew point and have to wait for the mirror to warm back up, so the method is normally slow and careful. Omix Plus first estimates the answer from everything else it just measured, then cools quickly toward that estimate and slows down only near the end. That is how a measurement that usually takes minutes lands in about 30 seconds.
Roast color
Color runs on roasted whole beans in Container B and on grounds in Container C, using near-infrared imaging to build the same kind of Agtron distribution Omni produces. Reading both whole beans and grounds is how you get a roast delta, the gap between the surface color and the interior the grind exposes. Swipe down on the result to move from the color wheel to the full distribution with its average and standard deviation.
The full Agtron scale runs 1 to 200. In practice, readings below about 30 mean essentially burnt coffee, and readings above 150 are rarely used, which is why the on-device chart windows sit at 30 to 150 for the full useful range, or 70 to 130 for specialty and competition, where most quality coffee lands.
Average and standard deviation - the average is the overall roast degree; the standard deviation is how uniform the roast is. A smaller number means a more even roast.
Display options: You can label color by SCA description or by common description, and pick the chart range that fits your work. The full 30 to 150 range in 10 point steps covers everything but is more than most specialty roasters need. A specialty range around 5 Agtron points per bar between 70 and 130 gives finer detail where specialty coffee actually sits, and a competition range covers the same 70 to 130 in 10 point steps for a quicker read.
Silver skin detection: Silver skin detection removes detected silver skin from the reading; turn it up and it catches more but risks a few false positives, turn it down and it is more conservative.
The roast standard below maps Agtron numbers to the SCA and common roast names.
| Agtron | Common | SCA |
|---|---|---|
| 0 – 30 | Espresso | Very Dark |
| 30 – 40 | French | Dark |
| 40 – 50 | Full City | Medium Dark |
| 50 – 60 | City | Medium |
| 60 – 70 | Dark | Medium Light |
| 70 – 80 | Medium | Light |
| 80 – 90 | Cinnamon | Very Light |
| 90 – 150 | Light | Extremely Light |
On-screen alerts
| Alert | Meaning |
|---|---|
| Container Abnormal | No empty Container A found in the base. Place one and continue. |
| Container Not Cleared | The container still has coffee in it. Empty it first. |
| Calibration prompt | The device sensed an ambient temperature shift. Recalibrate for accurate results. |
| Battery indicator red | One of the two batteries dropped below 15%. Charge the unit. |
Specifications
| Specification | Value |
|---|---|
| Functions | Roast degree, water activity, moisture, density, mesh, temperature and humidity, pressure and altitude, sample temperature, expansion rate |
| Supported samples | Coffee cherries, green coffee, parchment coffee, dried cherries, roasted coffee, ground coffee |
| Color | Range 1–150 Agtron, repeatability ±0.1 Agtron, resolution 0.1 Agtron |
| Water activity | Range 0.2–1 Aw, repeatability ±0.005 Aw, resolution 0.001 Aw |
| Moisture | Range 0–60%, repeatability ±0.1%, resolution 0.1% |
| Density | Range 0–1500 g/L, repeatability ±0.5 g/L, resolution 0.1 g/L |
| Volume | Range 0–1000 mm³, repeatability ±20 mm³ |
| Mesh | 9–25 mesh |
| Dimensions (L × W × H) | 120 × 120 × 170 mm |
| Weight (main unit + sample base) | 822 g |
| Screen | 3.5-inch HD touchscreen (70.08 × 52.56 mm) |
| Battery | Two lithium batteries (main unit and sample base) |
| On-device records | 1000 |
| Operating temperature | 0–45°C |
| Charging | USB-C, 5V / 2A |
| Connectivity | Bluetooth, Wi-Fi |
Accuracy vs repeatability. Accuracy is how close a reading sits to a known reference value. Repeatability, also called precision, is how much a reading moves when you measure the same prepared sample several times in a row, reported as a standard deviation or a max spread. It is the instrument’s own measurement noise.
For a quality-control spec, repeatability is the figure to build around. Batch-to-batch control limits like “hold this coffee to ±X Agtron” only mean something if they are wider than the instrument’s own repeatability. Set them tighter than that and you are chasing measurement noise, not real roast variation.
The figures in the table above are repeatability, taken across three repeat measurements of one prepared sample. Screen size returns an unchanged result across repeats.
Part 2: Omix Plus in CoffeeOS
On its own, Omix Plus gives you a reading on a screen. Paired with CoffeeOS, every reading attaches to a specific coffee and stays there. You measure a green lot once, and its moisture, water activity, density, screen size, and color follow that coffee through roasting, brewing, and every analysis you run afterward, so the data behind a cup is one tap away instead of scattered across notebooks and screenshots.
Connect and update
Power on Omix Plus near your phone and CoffeeOS detects it. Tap Connect. If new firmware is available it will offer the update; run it, since the device re-zeros afterward and you want it current before you measure.
CoffeeOS spots Omix Plus and prompts to pair. Tap Connect.
If an update is offered, install it. The device reboots and re-zeros when it comes back, so place empty container A while you wait.
Give it a nickname so it is easy to recognize, especially around other devices.
Device settings
Open Omix Plus in Device Center to reach its settings. About shows the device name, serial number, and firmware version. Test settings cover the measurement unit and the roast color standard. Calibration settings hold the calibration value, which is where you enter a new plate’s Agtron value if you replace Calibration Container D. You can also export your stored results to CSV from here.
The Omix Plus settings page: About, display, test settings, calibration value, and export.
Device name, serial number, and firmware version. A few controls, like the device language, are set on the device itself rather than in the app.
Add a green coffee to Bean Manager
Until Coffee Quality Analyzer ships, Omix Plus readings import straight into Bean Manager fields. Open Bean Manager, go to the Green tab, and tap the plus button to start a new entry. Give it a name, then work down the two sections: Crop Info and Bean Qualities.
Crop info from the bag
You can type crop info by hand, but the fast path is the bag itself. Tap Import, choose photo recognition, and take a photo of the bag. CoffeeOS reads the label and fills in what it finds: origin, process, variety, altitude, and anything else displayed on the bag. Confirm anything the bag left ambiguous, set your date received, and move on.
On a new green entry, tap Import in Crop Info and pick photo recognition.
Take a photo of the bag, or pull one from your library.
CoffeeOS fills origin, process, variety, and altitude from the label. Set your date received and adjust anything the bag left unclear.
Bean qualities from Omix Plus
Bean Qualities is where the measurements go. Open Edit Fields and turn on the metrics you want, screen size, size grade, average bean volume, water activity, moisture, density, and so on. Turn them all on, since Omix Plus can fill every one. Then tap Import, choose device autofill, pick your Omix Plus by name, set the sample type to Green Beans, and press Test. One run fills the whole set.
In Edit Fields, switch on the qualities you want recorded. Omix Plus can supply all of them.
Tap Import, choose device autofill, and select your Omix Plus from the connected devices.
Choose Green Beans so the device runs the right measurement set, then press Test.
One thing to watch: if water activity is set to run as a separate test on the device, a single autofill will not include it. Just open the water activity field and test it on its own. Then optionally add a bean description and save.
Moisture, density, screen size, volume, and color drop straight into Bean Qualities, ready to save.
Write anything worth remembering about the lot, then save the entry.
Update a coffee you already logged
If you added a coffee before you had it fully tested, you do not start over. Open the old entry, tap Edit, go to Bean Qualities, and import from device autofill, pulling either a fresh reading or the last result already stored on the device. Save, and the older entry now carries the full set.
Roasted beans and the link back to green
Roasted coffee lives on its own tab. When you add a roast, assign the green coffee it came from: tap Assign Beans, and pick the lot. CoffeeOS copies the crop info forward automatically.
On a new roasted entry, tap Assign Beans and choose the green lot it was roasted from.
The roasted entry inherits the same crop info automatically, linked back to the green coffee.
Add roast date, roaster, roast level, and charge temperature, then re-measure with Omix Plus to capture moisture loss.
How everything stays connected
Open a green coffee and you see every roasted batch made from it. Open a roasted batch and you see its recipe, the grinder and brew process behind it, and its Bean Insights, every brew, roast color session, and particle analysis run against those beans. Assign the same beans in a Roast Color Analyzer session, a Particle Analyzer sample, a Brew Recorder recording, or a Brew Controller session, and each result files itself back to the coffee. Nothing has to be matched up later.
Coming to CoffeeOS. Two tools will build on this. Coffee Quality Analyzer will track a bean’s quality over time instead of a single point-in-time reading, so you can watch moisture and water activity settle as a green lot rests and ages. Cupping Manager will tie every measurement back to the cup, linking color, density, and water activity to tasting and scoring. That link is the point of measuring at all: color and density inform roast decisions a roaster confirms on the tasting table, and these tools close the loop between the numbers and how the coffee actually tastes.
Color into Roast Color Analyzer
Omix Plus color readings flow into Roast Color Analyzer alongside Omni, CoffMeter A1, and OmniFlux. Open a session, assign the roasted beans, and the analysis ties back to the coffee like everything else. Each test averages whole-bean and grounds separately, so measure each one as many times as you need, then view your final color report including roast delta, and if your device supports the complete distribution, peak shift, and uniformity as well.
Start a new Roast Color Analyzer session.
Pick the roasted coffee, and every reading in the session ties back to it, and to the green lot behind it.
Reading roast color well is its own skill. A color number is not one fixed fact about a coffee; it is a value a method produces, which is why two devices can disagree and both be right. For how color is measured, why devices differ, and how to read a distribution, see the guide to color measurement.
Understanding Color Measurement in Coffee
Bulk density is not one fixed number
Because bulk density comes from weight over volume, and volume depends on how beans pack and how each device defines the sample boundary, the same coffee reads differently on different meters. That is expected, not a fault. Omix Plus multiplies its raw figure by a fixed factor so its output lines up with MD500, the reference meter already common in the trade. The point is continuity: your Omix numbers stay comparable to the readings and roast records people already keep, so relative trends hold even though absolute values differ between devices. Read bulk density as a consistent, comparable figure rather than a single physical constant.