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Amazfit · GTS Series · Zepp OS 2.0 · Launched October 2022
Amazfit GTS 4
The Amazfit GTS 4 is the fourth generation of Amazfit's rectangular smartwatch — adding Bluetooth phone calls, music storage, dual-band GPS, and a BioTracker 4.0 sensor to the GTS platform, while preserving the same slim 1.75-inch AMOLED display and lightweight aluminium design of its predecessor. The most fully-featured GTS yet, built for buyers who want a wrist-based all-in-one smart companion.
1.75" AMOLED · 341 ppi Bluetooth Calls 📞 Music Storage 🎵 Dual-Band GPS 8-Day Battery 150+ Sports Modes BioTracker 4.0 Route Import + Navigation Amazon Alexa SpO₂ · Heart Rate · Stress 5 ATM Water Resistant Zepp OS 2.0
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Bluetooth Phone Calls
Built-in speaker + mic — answer calls on your wrist
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Music Storage (2.46GB)
Store music on watch · play via Bluetooth headphones
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Dual-Band GPS
Industry-first circularly-polarized antenna · Route import
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8 Days (typical use)
4 days heavy use · 16hr GPS · ~28-day battery saver
GTS 3 (Step-Down) — The Light One
✔8.8mm thin · 24.4g — lighter than GTS 4
✔12-day battery (typical) — 50% more endurance
✗No Bluetooth calls · No music storage
✗Single-band GPS only
GTS 4 (This Watch) — The Complete One
✔Bluetooth calls — speaker + mic built in
✔Music storage — 2.46GB onboard for offline playback
✔Dual-band GPS + route import — real-time navigation
✔BioTracker 4.0 — 2LED sensor, 33% more health data
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Key Features

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Bluetooth Phone Calls
The GTS 4's most headline addition over the GTS 3 is its built-in microphone and speaker, enabling Bluetooth phone calls directly from the watch. When your phone is connected and nearby via Bluetooth, incoming calls ring on the GTS 4 — you can answer, speak, and end calls without touching your phone. The speaker is also on the left side of the case and the microphone is built into the frame. This is the first time the rectangular GTS line has offered call functionality, closing a gap that previously required a step up to the GTR 3 Pro. Note: real-world performance of the call feature varies by device pairing; some Android phones require a secondary Bluetooth pairing as a media device.
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Music Storage & Playback
The GTS 4 carries 2.46GB of usable onboard storage for music — you can load songs from your phone onto the watch via the Zepp app, then play them through the built-in speaker or paired Bluetooth headphones. For runners and gym users who want to leave their phone behind, this is a significant practical upgrade over the GTS 3. The watch also retains the music remote control function from the GTS 3 — controlling playback on your connected phone when you're not in offline mode. Combined with the speaker and mic, the GTS 4 functions as a genuinely self-sufficient wearable during workouts.
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Dual-Band Circularly-Polarised GPS
The GTS 4 introduces dual-band GPS — receiving both L1 and L5 satellite signals simultaneously across all six major constellations (GPS, GLONASS, Galileo, BDS, QZSS, NavIC). Amazfit describes it as using an industry-first circularly-polarised antenna design that achieves positioning accuracy 99% as precise as top handheld GPS units. In practical terms, dual-band GPS significantly reduces multipath errors — signal reflections off buildings and trees that degrade accuracy in urban canyons and forests. The GTS 4 also adds route import: you can load a GPX route file from the Zepp app to the watch and navigate it in real-time on your wrist without needing your phone.
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BioTracker 4.0 PPG Sensor
The GTS 4 debuts the new BioTracker 4.0 — Amazfit's fourth-generation PPG biometric sensor, upgraded to a dual-LED design that collects 33% more physiological data per sample compared to the single-LED BioTracker 3.0 in the GTS 3. The enhanced sensor enables more accurate 24-hour heart rate monitoring, more reliable SpO₂ readings, and improved stress level calculations via heart rate variability. Continuous monitoring runs throughout the day and night. One-tap health measurement (45 seconds) simultaneously measures heart rate, SpO₂, stress, and breathing rate — the same feature as the GTS 3, but with higher underlying sensor accuracy.
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1.75" AMOLED Display
The GTS 4 carries forward the identical 1.75-inch 390×450 AMOLED panel from the GTS 3 — same 341 ppi pixel density, same peak brightness, same tempered glass with anti-fingerprint coating. Reviewers note this as a sign of Amazfit's confidence in the panel rather than a cost-cutting measure; the GTS 3's display was already best-in-class for the bracket. Always-On Display is supported with matching AOD faces. The Zepp OS 2.0 update introduces two app menu layout options and two colour themes, adding more visual customisation flexibility over the original Zepp OS on the GTS 3. 150+ watch faces are available including animated and user-editable options.
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150+ Sports Modes & Strength Tracking
The GTS 4 maintains the 150+ sports modes of the GTS 3 and adds dedicated strength exercise recognition — the watch can intelligently identify strength training movements and log sets, reps, and effort automatically. Auto-detection covers the same eight sports as the GTS 3. Training analytics include VO2 Max, training load, recovery time, and training effect scoring. Workout data syncs to Strava, adidas Running, Komoot, Relive, Apple Health, and Google Fit via the Zepp app. A membership card store feature lets you add barcode and QR-code loyalty cards to the watch display — a practical daily convenience unique to the GTS 4 in the GTS line.
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Overview & GTS 3 vs GTS 4

Launched in October 2022, the Amazfit GTS 4 is the fourth generation of Amazfit's rectangular smartwatch and represents a more substantial feature upgrade over the GTS 3 than immediately apparent from the largely unchanged exterior. On paper, the two watches look almost identical — same rectangular case, same 1.75-inch AMOLED display with the same resolution and brightness — and placed side by side, most reviewers agree you genuinely cannot tell them apart at a glance.

The differences are entirely on the inside. The GTS 4 adds a speaker and microphone for Bluetooth phone calls, onboard music storage for offline playback, dual-band GPS with circularly-polarised antenna technology, route import and real-time navigation, the upgraded BioTracker 4.0 sensor, and Zepp OS 2.0 with expanded customisation. These are the features the GTS 3 was consistently criticised for omitting, and the GTS 4 addresses them all in one generation.

The cost of these additions is battery life — the GTS 4's 300mAh cell delivers an 8-day rated typical endurance versus the GTS 3's 12 days. In real-world use with AOD on and daily GPS exercise, expect 4–5 days. The case is also slightly heavier at 27–29g (body only) versus the GTS 3's 24.4g, reflecting the added hardware. For buyers who want the full smart companion experience — calls, music, precise navigation — the GTS 4 is the definitive GTS. For those who prize battery endurance and minimal weight above all, the GTS 3 remains the better option.

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Battery Life

8 days
Typical use (rated)
4 days
Heavy use (rated)
16 hrs
Continuous GPS
~28 days
Battery saver mode

The GTS 4's 300mAh battery is larger than the GTS 3's 250mAh, but the added drain from the speaker, mic, and dual-band GPS hardware brings the rated typical endurance down from 12 to 8 days. Real-world testing with AOD on and 30–60 minutes of daily GPS exercise typically yields 4–5 days. With AOD off, 6–7 days is achievable. The charging time remains approximately 2 hours via the proprietary magnetic dock — same as the GTS 3. There is no wireless charging on the GTS 4.

For context: 8 days rated is still dramatically better than daily-charge smartwatches like the Apple Watch (18–36 hours) and Samsung Galaxy Watch (up to 2 days). For buyers comparing within the Amazfit GTS family, the GTS 3's 12-day rating remains a meaningful practical advantage if you want to travel with minimal charging anxiety.

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What's New vs Amazfit GTS 3

🆕 Bluetooth Calls 🆕 Music Storage 🆕 Dual-Band GPS 🆕 Route Import 🆕 BioTracker 4.0 🆕 Strength Recognition 🆕 Zepp OS 2.0 🆕 Membership Cards
↑Speaker + microphone added (Bluetooth calls)
↑2.46GB onboard music storage added
↑Dual-band GPS (L1+L5) vs single-band on GTS 3
↑6 satellite systems vs 5 on GTS 3 (adds NavIC)
↑Route import + real-time navigation added
↑BioTracker 4.0 (2LED) vs BioTracker 3.0 on GTS 3
↑Strength exercise recognition added
↑Zepp OS 2.0 with dual layout + theme options
↑Membership/loyalty card storage added
↓Battery: 8 days typical (down from 12 on GTS 3)
↓Weight: ~27g body (up from 24.4g on GTS 3)
↓Same display: 1.75" 390×450 AMOLED (unchanged)
❤️

Health & Fitness Features

❤️ 24/7 Heart Rate 🩸 SpO₂ (Auto) 😤 Stress Monitoring 💤 Sleep Tracking 🔬 VO2 Max 📈 Training Load 💪 Strength Recognition 🚺 Menstrual Cycle
✔24-hour continuous heart rate (BioTracker 4.0)
✔Automatic SpO₂ blood oxygen monitoring
✔Stress monitoring (heart rate variability)
✔Breathing rate monitoring
✔Sleep tracking — stages, duration, score
✔VO2 Max estimation
✔Training load (7-day) + recovery time
✔Strength exercise recognition + logging
✔PAI Health Assessment System
✔Step counter · Distance · Calories burned
✔Menstrual cycle tracking
✔One-tap 45-second full health measurement
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Full Technical Specifications

Display
Display TypeAMOLED — Always-On Display supported
Size1.75 inches
Resolution390 × 450 pixels
Pixel Density341 ppi
GlassTempered glass — anti-fingerprint coating
Watch Faces150+ including animated · user-editable · custom photo upload
Design & Build
ShapeRectangular
Case MaterialAluminium alloy — one-piece middle frame
CrownGemstone-style stainless steel navigation crown (Amazfit logo)
Weight (body only)~27–29g (48g including strap)
Strap Width20mm — standard swappable
Strap MaterialsFluoroelastomer (Black, Rosebud Pink, Misty White) · Nylon (Autumn Brown)
ColoursInfinite Black · Misty White · Autumn Brown · Rosebud Pink
Water Resistance5 ATM (50 metres)
Battery
Capacity300 mAh
Typical UseUp to 8 days
Heavy UseUp to 4 days
GPS ContinuousUp to 16 hours
Battery Saver ModeUp to ~28 days
Charging TimeApprox. 2 hours (proprietary magnetic dock)
GPS & Sensors
GPS TypeDual-band (L1 + L5) — industry-first circularly-polarized antenna
Satellite SystemsGPS · GLONASS · Galileo · BDS · QZSS · NavIC (6 constellations)
Route ImportYes — GPX file import via Zepp app; real-time on-wrist navigation
SensorsBioTracker 4.0 PPG (2LED) · Accelerometer · Gyroscope · Geomagnetic · Barometric altimeter · Ambient light
Audio & Calls
SpeakerYes — built-in (left side)
MicrophoneYes — dual microphones
Bluetooth CallsYes — answer/end calls via Bluetooth to phone
Music & Storage
Internal StorageTotal storage (shared); 2.46GB available for music, apps, routes
Music PlaybackYes — onboard storage playback via built-in speaker or Bluetooth headphones
Phone Music ControlYes — remote control of phone's music player
Sports & Fitness
Sports Modes150+
Auto-Detection8 sports (same as GTS 3)
Strength TrackingYes — automatic strength exercise recognition (new vs GTS 3)
Swim TrackingYes — heart rate during swimming
Connectivity & Smart Features
BluetoothBluetooth 5.0 BLE
Wi-FiWLAN 2.4GHz
Voice AssistantAmazon Alexa (online) + offline voice assistant
NotificationsYes — calls, messages, app alerts (display + dismissal)
Membership CardsYes — barcode/QR loyalty cards (up to 20) via Zepp app
OSZepp OS 2.0
Compatibility
AndroidAndroid 7.0 and above
iOSiOS 12.0 and above
AppZepp (by Zepp Health)
Third-Party SyncStrava · adidas Running · Komoot · Relive · Apple Health · Google Fit
NFC / PaymentsNo
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Verdict

✅ What We Like
+Bluetooth calls + music storage in one watch — the GTS 4 is genuinely self-sufficient for a workout: calls, music, GPS navigation, and health tracking without your phone in hand
+Dual-band GPS with route import — L1+L5 dual-band is a meaningful real-world accuracy upgrade in urban and forested environments; route navigation on the wrist is a genuine outdoor utility feature
+BioTracker 4.0's improved sensor accuracy — the 2LED design delivers more reliable continuous health readings, particularly for SpO₂ and HRV-based stress monitoring
+Best-in-class display retained — the identical 1.75" 341ppi AMOLED panel means the GTS 4 inherits the GTS 3's screen without compromise; it remains one of the sharpest smartwatch displays available
+Excellent week-long battery for a feature-rich smartwatch — 8 days rated (4–5 real-world with AOD) still triples to quadruples the endurance of Apple Watch and most Wear OS devices
⚠️ Things to Know
−Bluetooth call reliability varies — multiple reviewers report pairing issues with certain Android phones requiring a secondary Bluetooth media device connection; the feature works but setup can be frustrating
−Battery life meaningfully shorter than GTS 3 — if you're choosing between the GTS 3 and GTS 4, the 8-day vs 12-day rating (4–5 vs 6–7 days real-world) is a real consideration for travellers or those who dislike charging frequency
−Zepp OS closed ecosystem — no Google Pay, no Google Maps, no app store in the traditional sense; Zepp OS is functional and smooth, but this is not a Wear OS or watchOS experience
−No NFC payments — neither the GTS 3 nor GTS 4 supports tap-to-pay; if contactless payments from your wrist are important, consider Samsung Galaxy Watch or Apple Watch instead
−Design virtually unchanged from GTS 3 — the exterior is near-identical to its predecessor; upgraders from the GTS 3 specifically may feel the visual progression is minimal for a new generation
Bottom Line

The Amazfit GTS 4 is the GTS 3 with everything the GTS 3 was criticised for missing — Bluetooth calls, music storage, dual-band GPS, and a better health sensor — in the same slim, light, beautiful package. For buyers new to the GTS series, the GTS 4 is the more complete, more capable, more self-sufficient watch and the natural choice. For buyers choosing between GTS 3 and GTS 4 specifically, the decision is straightforward: choose the GTS 4 if Bluetooth calls, music storage, or dual-band GPS matter to you; choose the GTS 3 if you want the lightest possible watch with the longest battery life and can live without those features. Both watches share the same outstanding display, health platform, and the best screen-to-body ratio in their class.