| Fitbit Alta HR | Fitbit Charge 2 | |
 |  | |
| Tech specs | ||
| Size | Device Dimensions: 15 mm x 10 mm x 35 mm (W x D x L) (Sizes depend on type of band) | Width: 21mm Small: 14 cm - 17 cm in circumference Large: 16.5 cm - 20.6 cm in circumference XL: 20.6 cm - 23.6 cm in circumference |
| Material | Wristband is made of a flexible, durable elastomer. The tracker is made with surgical-grade stainless steel, and the buckle is made with aluminum. | Stainless steel casing, elastomer strap |
| Charging | USB | USB. |
| Battery | Lithium-polymer | Lithium-polymer |
| Battery life | up to 7 days | up to 5 days |
| Water-resistance | Sweat, rain and splash proof | Sweat, rain and splash proof. |
| Weight | 15 grams | 36 grams |
| Sensor | 3-axis accelerometer, Vibration motor, optical heart rate sensor | Optical heart rate tracker, 3-axis accelerometer, altimeter, vibration motor |
| Display | B&W OLED touchscreen | OLED |
| Screen size | 1.4-inch, 128 x 36 pixel resolution | 3.8 cm |
| Colors | Black, Blue/Gray, Coral, Fuchsia | Black, Plum, Blue, Teal, Lavender Rose Gold, Black/Gunmetal |
| Other | ||
| Activity tracking | ||
| Steps | Yes | Yes |
| Distance | Yes | Yes |
| Calories burned | Yes | Yes |
| Activity | Yes | Yes |
| Floors | Yes | |
| Sleep | Yes | Yes |
| Heart rate | 24/7 | 24/7 |
| Stress & recovery | ||
| Pulse Ox | ||
| Respiration rate | ||
| UV exposure | ||
| Skin temperature | ||
| Galvanic skin response | ||
| Hydration level | ||
| Calorie intake | ||
| GPS | Connected GPS | |
| Running features | ||
| Swimming features | ||
| Other | Clock, auto sleep detection, silent wake alarm, auto exercise recognition. | Guided breathing |
| Non-fitness functions | ||
| Smartphone notifications | Yes | Yes |
| On-board music storage | ||
| Connected pay | ||
| LTE | ||
| Links | ||
| Affiliate link* | Amazon | Fitbit | Amazon | Fitbit |
| Read more | Review | Review |
**All tech specs and images on this page come from manufacturers. These may change over time as manufacturers sometimes update their devices. While we cannot guarantee absolute accuracy of information on this page, we promise to review this content regularly and do our best to bring you the most up-to-date information. To be absolutely sure of tech specs of a particular device, we recommend checking the manufacturer’s website.