Apple Watch Ultra 3 / Samsung Galaxy Watch5 Pro 45 mm

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 resists scratches better than mineral and aluminosilicate glass; the raised bezel around the screen protects the glass from knocks.

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.

Bioelectrical impedance analysis estimates values such as body fat and skeletal muscle; results are not for 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 covers surface water activities such as swimming, not diving or high-pressure water. MIL-STD-810H is a set of military test methods, not a guarantee of impact resistance.

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.

Samsung says the battery is 60% larger than the Galaxy Watch4’s.

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.

The D-Buckle band uses a folding clasp so the strap sits at the same point every time, in place of a standard pin buckle.

Wear OS 3 and later do not work with iPhone. Blood pressure and ECG work only in markets supported by Samsung Health Monitor and with Galaxy phones.

Track Back follows the recorded path in reverse to help you return to the start.