Galaxy Watch Ultra 2 vs Apple Watch Ultra 4: Your Phone Already Chose

Before comparing these two, be honest about the constraint. The Apple Watch Ultra 4 works only with an iPhone. The Galaxy Watch Ultra 2 works only with Android, and several of its health features need a Samsung phone specifically. For most people reading this, the phone in your pocket has already decided.

That still leaves three good reasons to compare them: you're switching phones and the watch is part of the decision, your household has one of each, or you want to know what the other side does better. Both are titanium, both are rated 10 ATM and certified for recreational diving to 40 m, both are cellular, and they weigh within 2 g of each other. The differences are in battery, health sensors, and what each one does when you're far from help.

The Spec Sheet

Battery figures are manufacturer claims, and the two measure differently: Samsung quotes 80 hours with the always-on display off and 60 with it on. In the US, the Galaxy Watch Ultra 2 comes in one configuration: 47 mm with LTE. Green marks the best in a row, shared when it's a tie.

The full spec sheets, including sensors, are on the Galaxy Watch Ultra 2 and Apple Watch Ultra 4 pages. The wearables comparison tool will add a Garmin to the lineup.

Where the Galaxy Watch Ultra 2 Is Ahead

Battery and price. Samsung quotes 60 hours with the always-on display running, against Apple's 50, and in independent testing the Ultra 2 beat its own claims comfortably. It also costs $100 less with LTE included. For a watch sold on outdoor credentials, that gap matters.

More health sensors. The Galaxy has a bioelectrical impedance sensor, so it can estimate body fat and skeletal muscle from your wrist. Treat the numbers like those from a bathroom scale: they move with hydration and time of day, so measure under the same conditions each time and watch the trend. The body fat calculator is a useful cross-check. Samsung also has a cuff-calibrated blood pressure estimate and a nightly Vitals report that tracks five overnight signals against your own baseline, none of it behind a subscription.

The build. The titanium case is 12% thinner than the last Galaxy Ultra, with sapphire crystal, IP69K and MIL-STD-810H ratings, and dive certification to 40 m. Decompression limits wait on a Mares dive app that Samsung says is due later this year. It's also the smaller and lighter of the two.

The blood pressure estimate needs the same caution as every cuffless reading. It's calibrated against a cuff and gets less reliable as your real pressure moves away from that calibration, which is when it would matter most (Stergiou et al., 2022). A validated arm cuff is still the reference, and the blood pressure calculator will put those readings in context.

Where the Apple Watch Ultra 4 Is Ahead

It works when you're alone. This is the Ultra's defining feature. Satellite Emergency SOS, Messages, and Find My all work from the watch with no iPhone nearby. Samsung has nothing like it. If you hike, climb, or run far beyond cell coverage, this is the one feature that can matter more than anything else on either spec sheet.

Heart tracking that never pauses. The Ultra 4's new sensing system reads heart rate every five seconds, all day, and turns it into a free daily Readiness score from 0 to 10. Apple's AFib detection was tested in one of the largest wearable studies ever run, with more than 400,000 participants (Perez et al., 2019), and the Ultra 4 adds hypertension and sleep apnea notifications. Apple chose to warn you about a pattern instead of showing a blood pressure number, which is the more cautious approach and the easier one to defend with evidence.

Charging and endurance modes. Fifteen minutes on the charger buys 18 hours, and two low-power workout modes stretch GPS tracking to 25 or 45 hours, still logging your position every second in the longer one.

Apple's weaknesses are the ones Ultra owners already know. There's only one 49 mm size, now 63 g, which is large on smaller wrists, and battery life is measured in days rather than weeks.

What Changed From the Older Ultras

Both watches replaced their predecessors this summer, and neither older model is sold new anymore, so you'll mostly find them discounted or refurbished.

The Galaxy Watch Ultra 2 is the first genuinely new Galaxy Ultra since 2024: thinner, with a 35% bigger battery, fast charging, and dive certification. The two older Galaxy Ultras are the same hardware, since the July 2025 refresh only doubled storage to 64 GB and added a Titanium Blue finish. At a good discount either is still a capable watch with the same 80-hour claim. Their spec sheets are on the Galaxy Watch Ultra (2025) and original Galaxy Watch Ultra pages.

The Apple Watch Ultra 4 keeps the Ultra 3's case, display, and satellite features, and adds eight hours of battery, five-second heart rate, and Readiness. A discounted Ultra 3 gets you the satellite features for less. What you give up is the battery and the new heart tracking.

What Neither Watch Is

Neither is a multi-week endurance watch. If you're choosing between them because you want a big titanium watch for training, and you'd switch phones for the right one, look at a Garmin as well. A Fenix E lasts 16 days and works with either phone. Both Ultras also share the limits of any wrist sensor. Optical heart rate is less reliable in stop-start efforts than in steady ones, and the wrist is a better place to track trends than to measure a single hard interval (Gillinov et al., 2017; Shcherbina et al., 2017). Use their VO₂ max estimates as a trend over months, not as a lab value.

So the decision is usually simple. On an iPhone, the Ultra 4 is the best watch you can buy for the outdoors, and satellite messaging is the reason. On a Samsung phone, the Galaxy Watch Ultra 2 gives you more battery, more sensors, and a lower price. Our guide to wearable health data covers which of their numbers are worth your attention.

References

1. Perez, M. V., Mahaffey, K. W., Hedlin, H., et al. (2019). "Large-scale assessment of a smartwatch to identify atrial fibrillation." New England Journal of Medicine, 381(20), 1909–1917.
2. Stergiou, G. S., Mukkamala, R., Avolio, A., et al. (2022). "Cuffless blood pressure measuring devices: Review and statement by the European Society of Hypertension Working Group on Blood Pressure Monitoring and Cardiovascular Variability." Journal of Hypertension, 40(8), 1449–1460.
3. Gillinov, S., Etiwy, M., Wang, R., et al. (2017). "Variable accuracy of wearable heart rate monitors during aerobic exercise." Medicine & Science in Sports & Exercise, 49(8), 1697–1703.
4. Shcherbina, A., Mattsson, C. M., Waggott, D., et al. (2017). "Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort." Journal of Personalized Medicine, 7(2), 3.