Fitbit Charge 6

Fitbit Charge 6 is a watch from 2023, sitting in the mid-range band at an indicative $159.

It reads 19 of the 33 signals this comparison tracks. Nothing at all from body composition. Rarer readings it does take: AFib detection, ECG recording and sleep efficiency.

By sensor class: 2 at clinical grade and 13 at consumer grade. That grade is my classification of the hardware, not a lab test. Those readings come from an optical heart rate sensor, ECG electrodes, an optical blood oxygen sensor, a skin temperature sensor, a GPS receiver and an accelerometer. It records an ECG and screens for atrial fibrillation. Those are screening features, not a diagnosis. Blood oxygen is measured through the night, not continuously through the day.

Its 7 days per charge are the 64th longest of the 74 devices of its kind here that publish a figure. The AMOLED screen can stay always on. Built-in GPS. Rated 5ATM / 50m, fine for swimming. It weighs 15 g. On top of the tracking it also handles music on the device and contactless payments. Case size 36.7x23.1x11.2mm. No subscription is required.

Flagship band; ECG + on-demand EDA, built-in GPS, no barometer (no floors).