Amazfit T-Rex Ultra vs Fitbit Versa 4
Amazfit T-Rex Ultra targets adventure enthusiasts with exceptional durability, rugged design, and extraordinary battery life reaching 20 days—ideal for extended outdoor expeditions. Fitbit Versa 4 emphasizes fitness tracking comprehensiveness with ECG capability, skin temperature monitoring, NFC payments, and Wi-Fi connectivity at a significantly lower price point. Display quality favors the T-Rex Ultra's higher resolution AMOLED (454x454 vs 336x336), while health sensors lean toward Versa 4's more complete suite. Battery performance isn't comparable—the T-Rex Ultra dominates with 20 days versus Versa 4's 6 days, requiring weekly charging. For budget-conscious fitness trackers prioritizing smart features and comprehensive health data, Fitbit Versa 4 delivers excellent value. However, outdoor adventurers needing minimal charging and extreme durability should choose the T-Rex Ultra, despite its premium price and missing ECG functionality.
Full Specifications
| Spec | Amazfit T-Rex Ultra | Fitbit Versa 4 |
|---|---|---|
| Software | Zepp OS 2.0 | Fitbit OS (transitioning to Wear OS) |
| Body | ||
| Weight | 89 g | 37.6 g |
| Case material | Stainless steel bezel, fiber-reinforced polymer case | Aluminum |
| Water resistance | 10 ATM, ISO 22810 certified for free-diving to 45m | WR50 |
| Health & Sensors | ||
| ECG | ||
| SpO₂ | ||
| Skin temperature | ||
| Heart rate | ||
| Sleep tracking | ||
| Battery | ||
| Battery life | Up to 20 days typical use, 80 hours GPS | Up to 6 days (typical usage) |
| Display | ||
| Size | 1.39 inch | 40 mm (1.58 inches) |
| Type | AMOLED | AMOLED |
| Always-on display | ||
| Resolution | 454 x 454 | 336 x 336 |
| Connectivity | ||
| GPS | ||
| NFC | ||
| Wi-Fi | ||
| Cellular | ||
| Bluetooth | 5.0 | 5.0 |
| Processor | ||
| Chipset | — | Fitbit proprietary |
Category Scores
Pros & Cons
Amazfit T-Rex Ultra
Pros
- Excellent 20-day battery life with always-on display
- Dual-band six-satellite GPS for high accuracy
- Rugged design with 15 military-grade certifications
- Free-diving rated to 45 meters
- Offline maps with route import support
Cons
- No ECG, skin temperature, or NFC payments
- No Wi-Fi or cellular connectivity
- Zepp OS app ecosystem is limited
- Heavier than most smartwatches at 89g
- No third-party app store
Fitbit Versa 4
Pros
- Best sleep tracking of any smartwatch — Daily Readiness Score
- ECG, SpO2, and skin temperature at $179 is strong value
- 6-day battery life — charge once a week
- NFC for Google Wallet contactless payments
- Google integration with Maps, Wallet, and YouTube Music
Cons
- Fitbit OS is being sunset — unclear future app support
- GPS accuracy is less reliable than Garmin or Apple Watch
- Limited third-party app ecosystem
- Physical button replaced with a haptic side button — divisive
Related Comparisons
Explore more in smartwatches, see all Amazfit products or all Fitbit products. View full details for the Amazfit T-Rex Ultra or the Fitbit Versa 4.