Owning a smartwatch means not only receiving notifications, but also carefully monitoring the body. The Xiaomi Watch S1 Active is equipped with advanced sensors that allow you to track key health indicators in real time. However, many users face difficulties in initially adjusting or interpreting data obtained from the wrist. It is important to understand that the accuracy of readings depends on the correctness of wearing the gadget and calibrating the sensors.
In this article, we will discuss how to activate the blood pressure measurement function if it is available in your area, or how to use alternative methods of monitoring through the pulse wave. Accuracy of data is critical for people who monitor hypertension or just lead an active lifestyle. We will look at the nuances of the PPG optical sensor and biometric information processing algorithms.
It is worth noting that the functionality may vary depending on the firmware version and regional binding of the device. The global version of Mi Wear or Mi Fitness may have limitations compared to Chinese software. So below we will look at all possible scenarios, including the use of third-party applications to synchronize data with blood pressure monitors, which is often the only right solution for obtaining medical accuracy.
Technical capabilities of the pressure sensor
The Xiaomi Watch S1 Active is based on an optical monitoring system that analyzes blood flow in the wrist. Unlike mechanical blood pressure monitors that use artery compression, smartwatches use light waves to estimate pulse wave, which means that direct pressure measurements in millimeters of mercury (mmHg) are not possible on all versions of the firmware and require complex calibration.
The main tool here is the PPG (Photoplethysmography) sensor, which shines through the skin with green or red light. AI algorithms analyze pulse rate and formula-based output values. Direct pressure measurement without a cuff on this model is available only in the Chinese version of the software and requires regular calibration with a mechanical tonometer. In global versions, the function is often replaced by monitoring stress and heart rate variability, which indirectly indicate the state of the vessels.
Users need to be aware of the difference between a medical device and a fitness tracker. The watch is great for tracking dynamics throughout the day, but not for making a diagnosis. If you see a sharp jump in indicators, do not panic - perhaps the clock just moved on your arm or you waved your hand abruptly. Always use a classic tonometer to confirm the data.
Why can’t the global version show pressure?
Preparation of the device for work
Before you start reading, you need to have the perfect conditions for the sensors to work. The density of the strap is the first and most important factor. If the watch hangs on the wrist, the light from the diodes will scatter, and the sensor will get a distorted picture of blood flow. The strap should be tightened so that the device does not shift when you are moving, but does not override the veins.
The second important aspect is the cleanliness of the sensor area: the back of the watch has sensor holes that are quickly contaminated with sweat, sebum or dust; regular wiping with a soft cloth without pile ensures that the light signal will pass without interference; and mud on the sensor is one of the most common causes of a measurement error message.
Also make sure that there are no tattoos on the wrist where the sensor is attached. Ink can block light waves, making reading impossible, in such cases it is recommended to shift the clock slightly higher or lower, to the area with clean skin, or use another method of health control.
- 🧼 Wipe the back of the watch with a soft dry cloth before each use.
- ⌚ Fasten the strap tightly but comfortably, leaving room for skin breathing.
- 📱 Make sure that the battery is over 15% for stable sensor performance.
- 🌡️ Let the clock acclimate if you just went out of the cold into the heat.
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If you have just returned from a workout, wait 10-15 minutes until your pulse and body temperature stabilize before taking your blood pressure.
Setting up the Mi Fitness app
The main control center for the Xiaomi Watch S1 Active is the Mi Fitness app (formerly known as Zepp Life for some models, but the S1 Active works with Mi Fitness), which is where the initial health profiles are set up. After pairing the watch with the smartphone via Bluetooth, you need to go to the Profile section and fill in your height, weight, age and gender data, these parameters are used by algorithms to more accurately calculate physiological parameters.
In Health or Monitoring, you should find a pressure or pulse item. If pressure is available, there will be an activation switch. In some cases, you need to turn on the Continuous Monitoring option so that the watch collects data in the background, which increases battery consumption, but gives a more complete picture of the daily rhythms.
It is important to check the firmware version of the watch through the app. Xiaomi regularly releases updates that can add new features or improve the algorithms of the sensors. Go to the device settings → System update and check for updates. If you are using iOS, make sure that the application is allowed access to background geolocation and notifications, otherwise the data synchronization may be interrupted.
☑️ Checking settings before measurement
Measurement process: step-by-step instructions
The process of reading on the Xiaomi Watch S1 Active is as simple as possible for the user, but requires a static position. First, unlock the watch screen and find the Health app or widget with a heart icon / tonometer. If the widget is not on the main screen, you can add it through a long press on the dial or in the app menu.
When you start the measurement function, you'll have a countdown timer on the screen, at which point the absolute immobility of your hand is critical, put your hand and your watch on the table with your palm down, or press it against your chest at heart level, and any muscle tension or finger movement can make noise in the signal and cause a Measurement failed error.
It usually takes 15 to 30 seconds, and when the sensor flashes green, it flashes intensely, and if the measurement is successful, you'll see two values: systolic (top) and diastolic (bottom) pressure, and pulse rate. If the watch gives you an error, try loosening and retightening the strap or changing your posture.
| Phase | User action | Clock reaction |
|---|---|---|
| 1. Launch. | Selection of the Health app in the menu | Turning on the green diode, vibration |
| Positioning | Put your hand on the table, relax your hand. | Countdown timer display |
| 3.Measurement | Don't move. 20-30 seconds | Intensive flashing of the sensor |
| 4. Outcome | Viewing data on the screen | Vibration of success, preservation in memory |
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The key to success is to be completely immobile for 30 seconds, and even micro-movements of the forearm muscles can distort the readings of the pulse wave.
Data interpretation and calibration
Once you get the numbers on the screen, it's important to get the numbers right. Normal blood pressure is 120/80 to 130/85 mm Hg at rest. However, there's a certain margin of error in a smartwatch. If you see values that are very different from your usual state, take your medication. First, double-check the data with a mechanical tonometer.
Calibration is the process of learning a watch to fit your body. Mi Fitness can have a manual input function. You measure pressure with a normal blood pressure monitor, then you put those numbers into the app. The algorithm calibrates its formulas to fit your physiology, which in the future will improve the accuracy of the clock. Without this procedure, the data can be averaged.
⚠️ Note: The indications of the smartwatch are informative. Do not use data from Xiaomi Watch S1 Active to adjust the dosage of drugs without consulting a doctor.
Also worth paying attention to heart rate variability (HRV). Low HRV values combined with an elevated resting heart rate can indicate fatigue or onset of illness, even if the pressure is formally normal. A comprehensive analysis of all indicators gives a more accurate picture than blood pressure numbers.
Possible errors and their solution
It's not uncommon for users to experience a watch that refuses to measure or that shows clearly incorrect data, and one of the common problems is cold skin, and when the ambient temperature is low, the blood vessels narrow and the blood flow in the wrist becomes weaker, making it difficult for the optical sensor to work, so you have to warm your hands by rubbing them against each other.
Another common mistake is having hair on your wrist or too pale/dark skin, which can affect light absorption. In such cases, the algorithm may not be able to cope with the noise. Try to move the clock 2-3 cm higher up your forearm, where the skin is usually thinner and hair is less frequent. Also make sure that there is no protective film on the screen that covers the sensors (although on the S1 Active they are usually open).
If the problem is software-based, rebooting the device will help. Press the power button 10-15 seconds before the Xiaomi logo appears. If that doesn't help, try untie the watch in the app and re-attach it by removing the old cache data.
- ❄️ Problem: Cold hands. Solution: Warm your wrist before measuring.
- 💇 Problem: Hair on the wrist. Solution: Move the clock higher or shave the site.
- 🔋 Problem: Low charge. Solution: Connect the watch to charging (measurement when charging may not be available, it is better to charge up to 20%).
- 📱 Problem: Synchronization error. Solution: Reboot Bluetooth on your smartphone.
Synchronization and analysis of statistics
All the data that you measure is automatically fed to the Mi Fitness app when you connect to your smartphone, and you can see the graphs of the day, week or month of pressure, and you can track circadian rhythms -- like how your blood pressure responds to your morning coffee, your stress at work, or your evening workout -- and you can see long-term statistics that are much more valuable than one-time measurements.
The app allows you to set targets and get alerts if your heart rate or (if available) blood pressure goes beyond the established limits, you can export data in PDF or CSV format to show it to your doctor at an appointment, which will save you from having to keep a paper diary of hypertension.
For advanced users, integration with Google Fit or Apple Health is available, which allows you to combine data from all your devices in one place, but it is worth remembering that when you transfer data between different ecosystems, some metadata can be lost or interpreted differently.
⚠️ Warning: When syncing with cloud services, make sure you use a secure Wi-Fi connection so sensitive medical data is not intercepted.