Apple Watch SE (2nd generation, 44 mm) / Samsung Galaxy Watch5 (40 mm, Bluetooth)

Weight is for the case only and rises with the band. The 44 mm case fits 140–245 mm wrists.

SE has no always-on mode; the screen wakes when you raise your wrist. Ion-X is strengthened glass and is not as scratch-resistant as sapphire.

Sapphire crystal is a glass material that strongly resists scratching. The 44 mm version has a 1.4-inch, 450 × 450 screen.

Storage holds music, podcasts and apps and cannot be expanded.

The high-g accelerometer and gyroscope are used for Crash Detection. ECG, blood oxygen and temperature sensors are not included on this model.

The electrical heart signal is used for ECG and bioelectrical impedance for body composition estimates; availability of these features varies by country.

Crash Detection can call emergency services after a severe car crash. Emergency SOS needs a cellular connection or Wi-Fi calling with internet access from the watch or a nearby iPhone.

Apple measures 18 hours with 90 time checks, 90 notifications, 45 minutes of app use and a 60-minute workout with music; on the cellular model, 4 of those hours are on LTE. Longer GPS workouts shorten it.

Suitable for swimming, but not for scuba diving, water skiing or high-velocity water sports.

The cellular model can make calls and use data without your iPhone nearby; carrier support is required.

The watch can only be set up and used with an iPhone; it does not work with Android phones.

WPC is the body behind the Qi wireless charging standard. The 44 mm version has a 410 mAh battery.

The watch works with phones running Android 8.0 or later with more than 1.5 GB of RAM; it cannot be used with an iPhone.

This version has no LTE; the LTE version is sold separately.

5ATM suits shallow-water activities such as swimming, not diving.