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Amazfit’s Zepp OS 3.5 was a 2024 smartwatch software update whose headline feature was Zepp Flow, a natural-language voice interface. The rollout began with the Amazfit Balance in February 2024 and expanded to selected Active, Cheetah, Falcon and T-Rex Ultra watches through June. It was not a universal update for every Amazfit watch, and the features varied by model and region. Zepp OS 4 followed in July 2024, so 3.5 is best understood as a major historical update—not the current software generation.
What Zepp OS 3.5 changed
Zepp Health announced Zepp OS 3.5 at Mobile World Congress in Barcelona on February 25, 2024. It was an operating-system update for compatible Amazfit watches, not a separate AI app. Its most prominent addition was Zepp Flow, which Amazfit described as an LLM-powered interface for giving a watch instructions in natural language. The announcement and initial rollout schedule are in Amazfit’s launch notice.
The update also brought interface and performance changes, plus model-specific additions to health, sports, navigation and customization. That distinction matters: getting Zepp OS 3.5 did not mean every watch gained every feature. Amazfit’s sports-watch update notes, for example, list outdoor and training features for supported models.
What Zepp Flow could do
Zepp Flow was intended to let users state an intention rather than remember a fixed voice command. Amazfit’s launch material described uses such as asking about health information or running pace, starting a workout, changing a watch setting or mode, and replying to supported messages. These are examples of the announced capabilities, not a guarantee that every phrase works on every watch.
#1 Best Overall
- STYLISH DESIGN, VIBRANT DISPLAY: The lightweight aluminum build blends effortless style with workout durability, while the vivid 1.97" AMOLED display keeps your data easy to read, even under bright sunlight.
- ALL-IN-ONE ACTIVITY TRACKING: The Amazfit Bip 6 fitness tracker watch offers 140+ workout modes including HYROX Race and Strength Training, plus personalized AI coaching and 50m water resistance.
- UP TO 14 DAYS BATTERY LIFE: The Amazfit Bip 6 smart watch powers through your training and recovery for up to two weeks at a time - no nightly charging needed.
- ACCURATE GPS TRACKING & NAVIGATION: Stay on course with free downloadable maps and turn-by-turn directions. Support from 5 satellite systems ensures precise tracking of every move and fast GPS connection.
- 24/7 HEALTH MONITORING: The Amazfit Bip 6 smartwatch provides precise, real-time monitoring of heart rate, sleep, blood-oxygen and stress, empowering you with actionable insights to optimize your health and fitness.
- Watch control: Ask the watch to start a workout or change a supported setting or mode.
- Health and fitness: Request relevant health information or workout data, subject to what the model and software expose.
- Messages: Reply to supported instant messages where the device, phone connection and permissions allow it.
- Outdoor use: On certain sports watches, use the update alongside navigation and training features.
“AI” here is a narrower claim than a general-purpose chatbot in a watch. Zepp Flow was a natural-language interface integrated with the Amazfit ecosystem; Amazfit did not establish that all voice processing happened on the watch. Some operations may be handled by the watch, while others may rely on a paired phone, network connection or cloud service. Do not assume the feature is entirely offline, or that every request can be answered without a phone.
Voice input also depended on hardware. For example, Amazfit’s T-Rex Ultra product page specifies Bluetooth headphones with a microphone for Zepp Flow voice commands. A voice interface therefore did not necessarily mean that the watch could hear speech through an onboard microphone. Check the requirements for the specific model.
Rank #2
- BIGGER DISPLAY. MAX CLARITY: Active Max features a shine brighter screen with a 3,000-nit display engineered for ultimate clarity, even under the harshest sunlight. See your data clearly on a large 1.5″ ultra-bright AMOLED display built for easy readability in any condition — from the gym to the mountains.
- BIGGER BATTERY, MAX ENDURANCE: Go longer between charges with reliable power built for every routine. With up to 25 days of battery, the Active Max smart watch keeps up with your routine day and night.
- BIGGER STORAGE. SMARTER MAPS: With 4GB of onboard storage, you have more space for your favorite music and downloaded maps with turn-by-turn directions — all accessible right from your wrist.
- BIGGER TRAINING, SMARTER INSIGHTS: From strength sessions to long runs, the Active Max tracker adapts to how you train with 170+ workout modes and personalized Zepp Coach running plans.
- BIOCHARGE ENERGY MONITORING: Your BioCharge score adjusts based on your daily workouts and stress levels to help you understand when to push harder and when to rest, so you can train smarter and recover better.
Rollout: models and announced dates
| Watch or family | Announced rollout |
|---|---|
| Amazfit Balance | Started February 26, 2024, in the United States, Canada, United Kingdom and Republic of Ireland |
| Amazfit Balance in additional European markets | Scheduled from May 1, 2024 |
| Amazfit Cheetah series | Rolling release scheduled May 28–June 11, 2024 |
| Amazfit Falcon | Rolling release scheduled May 28–June 11, 2024 |
| Amazfit T-Rex Ultra | Rolling release scheduled May 28–June 11, 2024 |
| Amazfit Active | Scheduled from June 20, 2024 |
These are announced rollout windows, not a promise that every watch in a region received the firmware on the same day. Availability could vary with model, region and firmware channel. Amazfit later described Zepp Flow expansion to Asia-Pacific (excluding Japan and Korea) and Latin America (excluding Brazil) in its Zepp Flow update notice.
The eventual support picture also changed after the initial announcements. A later Amazfit update listing referenced Zepp OS 3.5 updates for the GTR 4 and GTR 4 Limited Edition. That makes an early “GTR 4 is unsupported” statement too broad as a permanent claim; it does not establish that every feature was available on those watches. See the later update reference. For any model not listed above, check its current firmware information in the Zepp app rather than inferring eligibility from its age or product family.
Rank #3
- STYLISH DESIGN, BRIGHT DISPLAY: The sleek stainless steel build blends classic style with workout durability, while the bright 1.32" AMOLED display keeps your data easy to read, even under bright sunlight.
- PRECISE HEART RATE AND SLEEP TRACKING: Amazfit's BioTracker technology tracks your heart rate and sleep data with accuracy that previous sensors just can't match.
- UP TO 10 DAYS OF BATTERY LIFE: With long battery life that lasts up to 10 days with typical use, nightly recharges are a thing of the past.
- FREE MAPS WITH TURN DIRECTIONS: Stay on-track with free downloadable maps, and get turn-by-turn guidance on-screen or via your Bluetooth headphones. Enjoy ski maps for global resorts, including guidance for cable cars, slopes, and more.
- FASTER AND MORE ACCURATE GPS TRACKING: 5 satellite positioning systems ensure fast GPS connection and accurate positioning whenever you're out running, walking, cycling or hiking.
Extra features for sports and outdoor watches
For the sports and outdoor watches covered by Amazfit’s June update, Zepp OS 3.5 was about more than Zepp Flow. Listed additions included contour maps, turn-by-turn directions, a night display mode, customizable data plugins, HRV tracking, Readiness-related features, external bike-speedometer support and Bluetooth control of the DJI Osmo Action 4. These features were model-specific; consult the official feature notes for the models they cover.
Contemporary launch coverage reported that Alexa, Zepp Coach and Zepp Aura were expected to remain alongside Zepp Flow, rather than being replaced by it. Availability of those services can depend on device and region; see launch coverage for that contemporary account.
Rank #4
- DUAL-BAND GPS & OFFLINE MAPS: Navigate confidently with dual-band positioning and six satellite systems. Use offline maps, turn-by-turn navigation, and automatic rerouting to stay on track without your phone.
- 21-DAY BATTERY: Get up to 21 days of battery life on a single charge, and never worry about forgetting your charger on trips. Enjoy long battery life performance from work, to workouts, to weekend trips.
- AMOLED SCREEN & BUILT-IN FLASHLIGHT: A large 1.5" AMOLED screen protected by sapphire glass is easy to read in bright daylight or night. Stay safe and visible in low-light conditions with the built-in white or tactical red flashlight.
- NO SUBSCRIPTION APP: Health, recovery, and workout data is free to access in the included Zepp App. Track calories and protein goals.
- APP CONNECTIONS & HYROX TRAINING: Use fitness apps like Strava, TrainingPeaks, Intervals.ICU to share workouts. Improve HYROX training with built-in HYROX training plans and Virtual Pace simulations.
How to check for the update
- Open the Zepp app on the phone paired with your watch.
- Go to the profile or device section and select the watch.
- Open its firmware or system-update area and check for available software. Labels can differ between app versions.
- Keep the watch paired, the phone nearby with Bluetooth enabled, and the watch adequately charged while the update downloads and installs.
- Let the watch finish any restart, then verify its firmware version in the app or watch settings.
If no update appears, first confirm the exact watch model and check again later: the rollout was staged. If installation fails, restart the phone, watch and Zepp app, reconnect, and retry without interrupting the transfer or reboot. If Zepp Flow is missing after updating, check regional and language availability, any separate feature update, required headset hardware, and relevant phone and app permissions. Exact requirements can differ by model.
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What to expect—and what not to assume
Natural-language control can be convenient when hands are occupied, but it is not automatically more reliable than using the watch’s menus. Speech recognition may mishear names, settings or workout choices. Check the result, especially before sending a message or changing an activity setting. Because the launch material does not establish a complete processing architecture, it also does not support promises that conversations are processed only on the watch or that the feature works without a phone or internet in every situation. Review device permissions and the applicable privacy information for your region if those details matter to you.
Best Value
- ULTRA-BRIGHT AMOLED DISPLAY: With peak brightness of 2,000 nits, the Amazfit smart watch delivers easy reading of maps and workout data in any light. Night mode and Glove Mode enhance visibility for clear viewing
- DURABILITY FOR EXTREME CONDITIONS: This rugged smart watch, engineered with a 316L stainless steel bezel, withstands temperatures from -22F to 158F, and is water-resistant to 328 feet and can be used for freediving to a depth of 147 Feet
- EXTENDED BATTERY LIFE: The Amazfit T Rex 3 offers over 3 weeks of power with typical use or up to 180 hours in GPS mode, providing long-lasting performance for hiking trips or outdoor activities
- PRECISION NAVIGATION TOOLS: The smart watch for men and women provides free global maps with dual-band positioning. Six satellite systems offer fast, accurate GPS connections and precise turn-by-turn navigation
- EXPANSIVE FITNESS TRACKING: This fitness watch offers 170plus workout modes and AI-generated training plans, providing real-time updates to guide your fitness journey from hiking to surfing
Finally, a Zepp OS 3.5 update did not guarantee access to later Zepp Flow features or to the next operating-system generation. Zepp Health announced Zepp OS 4 on July 2, 2024, describing an upgraded Zepp Flow experience with OpenAI’s GPT-4o. That announcement does not mean every 3.5-compatible watch received OS 4. Read the Zepp OS 4 announcement and check your individual watch’s current firmware before treating any version as available to it.
Quick Recap
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