RS Extract
Professional Coffee TDS Refractometer
Preorders shipping now
Preorders ship first
The first run sold out and is on its way to preorder holders now. Order today and yours ships with the next run on 8 November.
Early-bird price until 8 November, 11:59 pm Pacific.
Own R1 Extract or R2 Extract? Owners pay as little as $479.00. Get your code before you buy.Own R1 or R2 Extract?
Thank you for measuring with us. Owners take an extra discount on RS Extract and every RS kit, on top of the early-bird price.
DiFluid Coffee counts as R1 Extract
One code per owner, used once. Own both? You get the R1 price.
- Tick your deviceTick R1 Extract or R2 Extract on the loyalty page.
- Get your codeYour code shows straight away.
- Enter it at checkoutAdd RS Extract or an RS kit to your cart and enter the code at checkout.
What it does
Reads coffee hot, from 4 to 65 °C. RS Extract is a professional coffee refractometer for people whose measurements other people rely on: roasteries, training labs, quality teams, competitors and field service. Pour the sample straight from the brew and read it. Cooling Curve Compensation uses the room temperature and the temperature in the well to work out where the reading settles, so there is no pipette rinse, no waiting for the sample to cool, and no evaporation creeping into the result.
- ±0.02% TDS repeatability, on a refractive index resolved to 0.00002
- 0 to 30% TDS, so filter and espresso are measured on one device
- Extraction yield on the device: enter dose and beverage weight on the 3.5-inch color touchscreen and read EXT% beside TDS on the brew control chart
- 500 stored readings
- A magnetic lid seals the well while it reads, and doubles as the dust cap
- IP67, 13 hours of continuous measuring, USB-C charging
- Connects to CoffeeOS over Bluetooth, so each reading can be linked to the brew and the bean it came from
Shipping since 25 October 2026. Preorders are on their way. Orders placed now ship with the next run on 8 November.
Alongside R2 Extract
What's new
RS Extract grew out of R2 Extract. These are the rows where RS Extract does something R2 Extract cannot.
| Specification | R2 Extract | RS Extract |
|---|---|---|
| Sample temperature | 20–40 °C | 4–65 °C |
| Cooling step | Required for anything hot | None |
| Display | Monochrome | 3.5″ color touchscreen |
| Extraction yield | Phone required | On the device |
| Stored readings | Phone required | 500 on the device |
| Evaporation control | Open well | Magnetic sealing lid |
| Languages on the device | Numbers only | English, Chinese, Japanese, Korean |
| Battery | 430 mAh · 12 h | 3000 mAh · 13 h continuous, 16 h standby |
| Ambient operating range | 5–40 °C | 5–45 °C |
For you
RS Extract in your work
A figure that travels.
Read the cup at origin, at whatever temperature the mill's lab room happens to be, and send the figure with the sample. In CoffeeOS it is saved with the moisture, density and color readings for the same lot.
Matching readings at both ends.
Because a sample can be read hot or cold, a reading at origin and one at destination are taken the same way, and with five hundred records on the device you can trace the pair months later.
Pre-shipment against arrival.
In CoffeeOS, extraction is saved with moisture, density and roast color for the same lot, so you can compare a pre-shipment sample with the landed lot directly.
A reading for every cup.
No cooling step between cups keeps the table moving, and averaging repeats means one odd sample never becomes the score.
Every batch, at the brewer.
±0.02% repeatability is how you know a profile change was real. Five hundred readings on the device is a full production day of sign-offs, taken at the brewer and synced to CoffeeOS when you want them.
Every shift reads the same.
The morning bar and the evening bar give comparable figures, because the reading does not depend on how long someone waited. Extraction on the screen means a spec check needs no training.
One variable at a time.
Repeatability to ±0.02% TDS is what separates a real change from noise, so one grind step shows up as itself and you stop turning two knobs at once. A whole bag's dial-in sits on the device as a list, filter and espresso on the same 0 to 30% range, and the chart is on the screen rather than behind an app.
Compare roasts fairly.
Cups from two roasts are read the same way, so the difference between the figures came from the roast. That is the point of keeping the TDS.
Extraction before the class ends.
Reading each brew hot, with no cooling step, means six brews per student inside a ninety-minute session, and the chart is on the screen in the room.
Practice runs you can compare.
Read each practice shot hot, with ±0.02% TDS repeatability and extraction calculated on the screen. Ninety seconds between shots is enough.
Specs
| Measurement range | 0–30% TDS |
|---|---|
| Repeatability | ±0.02% TDS |
| Accuracy | ±0.02% TDS from 0 to 4.99%, ±0.04% from 5 to 20%, ±0.06% from 20.01 to 30% |
| Resolution | 0.01% TDS |
| Refractive index range | 1.33299–1.38660 |
| Refractive index resolution | 0.00002 |
| Refractive index repeatability | ±0.00004 |
| Reading time | Under 4 seconds. Hot or iced samples take a little longer. |
| Sample temperature | 4–65 °C |
| Operating temperature | 5–45 °C |
| Display | 3.5″ color touchscreen |
| Stored readings | Up to 500. When full, the oldest is replaced. |
| Battery | 3000 mAh · 13 h continuous, 16 h standby |
| Charging | USB-C, about 4 hours to full |
| Water resistance | IP67 |
| Connectivity | Bluetooth, to CoffeeOS and DiFluid Microbalance scales |
| Size | 150 × 72 × 28 mm |
| Model | DFT-RS01 |
In the box
- RS Extract
- Magnetic lid
- Charging cable
- Coffee spoon
- Quick start guide
- QR code card
- Product information card
Questions
Can RS Extract read coffee while it's hot?
Yes. It reads samples from 4 to 65 °C, straight from the brew. Cooling Curve Compensation uses the room temperature and the temperature in the well to work out where the reading settles, so there is no waiting for the sample to cool.
Can it measure espresso?
Yes. The range runs from 0 to 30% TDS, so filter and espresso are measured on one device. Espresso carries oils and fines, so filter the shot through a 0.45 µm PES syringe filter (sold separately) and read it within a minute.
What water should I zero it with?
Distilled water when the figure is going to someone else, because the reference stays the same wherever it is read. Your brewing water when you want the reading to show only what the coffee added. Once a week is enough in most places. Zero more often where temperature and humidity swing.
Does it calculate extraction yield?
Yes. Enter the dose and the beverage weight on the touchscreen and EXT% appears beside TDS on the brew control chart. Connected to a DiFluid Microbalance scale over Bluetooth, it reads the beverage weight for you.
How many readings does it keep?
Up to 500 on the device. When it is full, the oldest reading makes room for the newest. Connect it to CoffeeOS to keep every reading and link each one to the brew and the bean it came from.
Is it waterproof?
It is rated IP67, so spills on a busy bar won't hurt it. Clean the well with a soft, damp cloth after each reading, and don't use alcohol, acetone or other harsh cleaners.
RS Extract on its own, or a kit?
RS Extract on its own measures TDS and extraction. Brew Control System RS adds Microbalance Ti, which records dose, yield and the flow of the pour. Sensory Brew Control System RS adds Moment, so you can taste by temperature. Sensory Brew Control System Ultimate RS adds Omni, which measures the particle size distribution of your grind.
Does it work with CoffeeOS?
Yes. RS Extract connects to CoffeeOS over Bluetooth, and each reading can be saved to the brew and the bean it came from. CoffeeOS is free on iOS and Android.
When will it ship?
I own R1 Extract or R2 Extract. Do I get a discount?
Until 8 November, 11:59 pm Pacific, owners take an extra discount on top of the early-bird price. Tick your device on the loyalty page and your code shows straight away. Get your code
What if it isn't right for me?
You can return it within 30 days of delivery if it is unused and in its original packaging. Email service@digitizefluid.com with your order number first, and we'll send the return instructions. If the problem is a fault or our mistake, we cover the return shipping.
What does the warranty cover?
For one year from the date of purchase, faults that occur under normal use are repaired or replaced free. After that we still repair it, at a cost that depends on the damage. Email service@digitizefluid.com with a description, a short video and the serial number.