Polar M400 vs. Amazfit Stratos vs. Fitbit Charge 3 vs. Xiaomi Mi Band 4 vs. Amazfit T-Rex
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| PolarM400Remove Buy Now | AmazfitStratosRemove Buy Now | FitbitCharge 3Remove Buy Now | XiaomiMi Band 4Remove Buy Now | AmazfitT-RexRemove Buy Now |
Basic Info | |||||
| Suggested Price | $200 | $199 | $150 | $25 | $140 |
| Release | 2014 | 2018 | 2018 | 2019 | 2019 |
Activity & Fitness | |||||
| Calories | |||||
| Cycling (Bicycling) | |||||
| Distance | |||||
| Heart | n/a | ||||
| Oxygen | |||||
| Sleep | |||||
| Steps | |||||
| Swim | |||||
Battery | |||||
| Duration | 8 hours to 30 days | 5 days | 7 days | 20 days | 20 days |
| Rechargeable | |||||
Compatibility | |||||
| Android | |||||
| iOS | |||||
| Windows Phone | n/a | ||||
| Mac | |||||
| Windows | Not yet | ||||
Connectivity | |||||
| Bluetooth | |||||
| Cellular | |||||
| GPS | |||||
| NFC | NA | ||||
| Wi-Fi | |||||
Display | |||||
| Color | |||||
| Resolution | n/a | 320 x 300 | 66 x 18 | 120x240 | 360 x 360 |
| Size | n/a | 1.34 inches | .721 inches | 0.95 inches | 1.3 inches |
| Touch | |||||
| Type | n/a | OLED | OLED | AMOLED | AMOLED |
Functions | |||||
| Audio Speaker | Alerts only | ||||
| Clock | |||||
| Phone | |||||
| Vibration | |||||
| Voice | |||||
Hardware | |||||
| Accelerometer | |||||
| Barometer or Altimeter | |||||
| Ultraviolet Sensor | |||||
| Water Resistance | 3 ATM | 5 ATM | 5 ATM | 5 ATM | 5 ATM |
Notifications | |||||
| Phone | |||||
| Emails | |||||
| Texts | |||||
Software | |||||
| Operating System | n/a | Proprietary | NA | AMAZFIT OS | Build-in |
| Apps | |||||
| Music | |||||