Acclimation compares your blood oxygen saturation (SpO2) with the values statistically expected at your current altitude. It then estimates your acclimatization level based on your recent altitude history, rather than looking only at your current reading. ### How it works Seven percentile curves, from P2.5 to P97.5, describe the expected SpO2 range at different altitudes. The app uses your barometric altitude and current SpO2 to determine where your reading falls within this distribution. The app then estimates an acclimatization altitude, which represents the altitude your body has progressively adapted to based on your recent exposure. This value increases with time spent at altitude and decreases when you descend, with different rates for ascent and descent. The model is based on the general principles of ventilatory acclimatization described in altitude physiology research. Your overnight SpO2 can further refine the estimate. A good night can increase the acclimatization estimate, while a lower reading will not directly decrease it. ### Three views **Dial** Shows your current SpO2 and altitude, along with your position on the percentile scale. **Thresholds** Shows the same information while displaying the expected SpO2 value for each percentile around the dial. **Acclimatization** Shows your estimated acclimatization altitude, its recent trend and the difference between your current altitude and your estimated acclimatization level. ### Designed for battery life and reliable measurements Acclimation does not continuously trigger SpO2 measurements. It uses measurements that your watch has already taken and only requests a new reading when the previous one is too old or when your altitude has changed significantly. The acclimatization model only uses overnight SpO2 measurements. These readings are generally more stable and less affected by movement. Manual SpO2 entries are not used for this calculation, keeping the model based on actual sensor data. ### Settings and compatibility You can choose between meters and feet, adjust the dial between proportional and equal-width display, set the maximum age of a SpO2 reading and enable a vibration alert when your value falls below a selected percentile. The app is available in French and English on a selection of Garmin watches with a color display and barometric altimeter, including fenix, epix, Forerunner, Venu, vívoactive, Descent, Enduro and D2 models. Check the product listing for the complete compatibility list. ### Feedback Acclimation is developed with feedback from people who actually use it in the mountains. If something feels wrong, a feature is missing or you encounter a problem with your watch, feel free to get in touch. Every message is read. This app is not a medical device. It does not diagnose medical conditions or prevent acute mountain sickness and should not be used as a substitute for medical advice. It is intended for informational and educational purposes. If you experience symptoms at altitude, seek medical advice and consider descending.

v6.2.2 : « Watchdog Tripped - Code Executed Too Long » (PATCHED) v6.2.1: Model calibration: ascent constant reduced from 120 h to 72 h, and nighttime correction weight increased from 15% to 25%. The model was calibrated through simulations to better match realistic ascent profiles while giving greater weight to good nighttime SpO₂. Nighttime correction improved: the correction is now based on the nighttime altitude and z-score, making it monotonic and ensuring it never exceeds the actual nighttime altitude. 20 watches added: fenix 8, fenix E, Enduro 3, Forerunner 970/570, Venu 4, Venu X1, Instinct 3 AMOLED, D2 Mach 2/2 Pro, and Descent G2/Mk3, including their supported variants. Device compatibility: vivoactive 6 was excluded, while vivoactive 5 and Venu Sq 2 were removed because their SDK profiles do not provide altitude history due to the lack of a barometer.