Apple Watch Ultra 3 / Samsung Galaxy Watch8 Classic (46 mm, Bluetooth)

Ultra 3 is sold only as a 49 mm GPS + Cellular watch; bands fit 130–210 mm wrists.

Apple says the wide-angle OLED pixels emit light at wider angles, so the screen stays readable without fully turning the wrist. LTPO3 allows thinner borders and lets the always-on mode refresh once per second, so a seconds hand is visible without raising the wrist. The 1-nit minimum reduces glare in the dark.

Sapphire crystal is a cover material that resists scratches better than ordinary glass.

RedCap is a reduced form of 5G for low-data devices such as watches. Satellite connectivity lets you call for emergency help and send short messages outside cellular coverage; Apple says Find My shares location via satellite every 15 minutes. Satellite services are free for two years from activation; Find My and Messages need a carrier plan, and availability varies by region.

Using L1 and L5 together helps reduce reflected-signal errors near tall buildings and under tree cover. Ultra Wideband availability varies by region.

The electrical heart sensor powers the ECG app; the optical sensor drives heart rate and Apple’s hypertension notifications. Hypertension notifications passively analyse 30-day periods and are not intended for people under 22, during pregnancy or for those already diagnosed. The temperature sensor is not for medical use; the Blood Oxygen app is for wellness use.

Health features are for general wellness and fitness, not medical diagnosis.

Diving needs a compatible third-party app; the depth gauge is accurate to ±1 m. MIL-STD 810H covers altitude, high/low temperature, temperature shock, immersion, freeze/thaw, ice and freezing rain, shock and vibration. Passing these tests does not mean the watch cannot be damaged.

5ATM suits surface water use such as swimming, not diving or high-speed water sports. Samsung says its MIL-STD-810H testing cycled the watch between –20 °C and 50 °C for 6 hours in total.

Apple says 15 minutes of charging gives 12 hours of normal use and 5 minutes gives 8 hours of sleep tracking. Apple’s 80% in 45 minutes figure is based on its 20 W USB-C power adapter. Low Power Mode is rated at 20 hours of continuous outdoor workout with full GPS and heart rate.

The siren helps people nearby locate a user who is lost or needs help.

The watch does not pair with Android phones; setup and most features require an iPhone.

It is sold in one size only.

The rotating bezel lets you scroll lists and apps without touching the screen; its position is read by a 3D Hall sensor found only on the Classic. Quick Button can be assigned to an app or function.

Samsung says its charge times were measured with a separately sold 25 W adapter.

Setup and use need an Android 12 or later phone with more than 1.5 GB of memory and Google Mobile Services.

The second frequency (L5) helps accuracy where signals bounce, such as among tall buildings or under trees.