Apple Watch Ultra 3 vs Garmin fēnix 8

Garmin announced the fēnix 8 on 27 August 2024, and Apple’s Ultra 3 followed on 9 September 2025. Both now have successors, fēnix 9 and Ultra 4, so this is a choice between two previous-generation adventure watches. Garmin released the fēnix 8 in 43mm, 47mm and 51mm AMOLED sizes, plus Solar versions, and each has its own battery ratings; the Garmin numbers that follow are for the 47mm AMOLED.

Side by side

Spec	Apple Watch Ultra 3	Garmin fēnix 8 (47mm AMOLED)
Announced	9 September 2025	27 August 2024
Works with	iPhone 11 or later	iPhone or Android (Garmin Connect)
Case	49 × 44 × 12mm Grade 5 titanium	47mm; thickness not published
Weight	61.6 g natural; 61.8 g black	Not published
Display	LTPO3, 422 × 514, 3,000 nits	AMOLED; resolution and brightness not published
Chip and storage	S10, 64GB	Not published
Smartwatch battery	Up to 42 hours normal use	Up to 16 days with gesture; 7 days always-on
Low-power mode	Up to 72 hours	Up to 23 days battery saver
GPS battery	No workout rating given	47 hours GPS-only; 35 hours multi-band
GPS	Dual-frequency L1 and L5	Multi-band with SatIQ
Maps	Offline maps; U.S. topo maps; 63 national parks	TopoActive on sapphire models; others download maps
Satellite	SOS, Messages, Find My	None; no inReach
Water and diving	100m; EN 13319 to 40m	10 ATM; 4 ATM dive; EN 13319 to 40m
Flashlight	Yes	LED with red light and strobe
US launch price	$799	Series from $999.99

Start with your phone

Ultra 3 doesn’t work with Android. It needs an iPhone 11 or later, including iPhone SE (2nd generation or later), on iOS 26 or later, and the watchOS 27 update it qualifies for needs iOS 27. You get Apple Pay, GymKit and the watchOS apps, but not a watch you can move to a Galaxy or Pixel phone later.

The fēnix 8 pairs with an iPhone or an Android phone through Garmin Connect, which handles notifications, music services, Garmin Messenger and LiveTrack, so it keeps working if you switch. You give up watchOS apps and Apple’s satellite messaging. Garmin Pay depends on your country, network and bank, and the strap fitting is Garmin’s QuickFit rather than Apple’s Ultra band system. It takes calls through its own speaker and microphone while paired, but it has no cellular radio.

Hours against days

Apple rates Ultra 3 for up to 42 hours of normal use and 72 hours in Low Power Mode, and gives it no GPS workout rating. The magnetic fast charger to USB-C gets it to about 80 percent in 45 minutes, and short top-ups help: 15 minutes adds about 12 hours of normal use, and 5 minutes about 8 hours of sleep tracking.

Garmin rates the 47mm fēnix 8 in days, with separate figures for a screen that wakes when you raise your wrist (gesture) and one that stays on:

Mode	Gesture	Always on
Smartwatch	Up to 16 days	Up to 7 days
Battery saver	Up to 23 days	Not applicable
GPS only	Up to 47 hours	Up to 37 hours
All satellite systems	Up to 38 hours	Up to 30 hours
All systems plus multi-band	Up to 35 hours	Up to 28 hours

GPS with music is rated for 10 hours, Max Battery GPS stretches to 81 hours, and Expedition mode to 17 days. Garmin’s only charging guidance is to charge between 0 and 45 degrees Celsius; there’s no quick top-up figure to set against Apple’s.

Keep the tests apart when you compare. Ultra 3’s 42 hours is Apple’s normal-use day; the fēnix’s 16 days is smartwatch mode with the screen waking on a wrist raise, not 16 days of GPS. With multi-band GPS on, the 47mm fēnix 8 is rated for 35 hours. If a listing promises 29 days, that’s the 51mm AMOLED, and longer smartwatch figures with solar charging belong to the Solar models.

Satellite is the safety difference

Ultra 3 sends Emergency SOS, Messages and Find My over satellite when there’s no cell signal, and Apple includes that free for two years after activation. The 47mm fēnix 8 has no satellite radio and no inReach. Its incident detection, assistance and LiveTrack go through your paired phone, and Garmin Messenger handles two-way texts only when both people have the app. If a fēnix 8 listing promises satellite SOS on the watch itself, it’s describing a Pro or a newer fēnix.

Screen, size and weight

Ultra 3’s LTPO3 screen is 422 by 514 pixels at 326 pixels per inch, with 1,245 square millimeters of active area. It peaks at 3,000 nits and dims to 1 nit. The titanium case measures 49 by 44 by 12 millimeters, weighs 61.6 grams in natural or 61.8 grams in black, and fits wrists from 130 to 210 millimeters. Inside is the S10 chip with 64GB of storage.

Garmin doesn’t give the 47mm fēnix 8’s resolution, brightness, weight, thickness or storage. If a listing shows 64GB or a 3,000-nit screen, it’s describing a fēnix 9 or a Pro model, not this watch.

Maps and GPS

Ultra 3 uses precision dual-frequency GPS on the L1 and L5 bands, with GPS, GLONASS, Galileo, QZSS and BeiDou; Apple calls it the most accurate GPS in a sports watch. For hiking it has a compass, waypoints, Backtrack, offline maps, U.S. topographic maps and curated hikes across all 63 U.S. national parks.

The fēnix 8 has multi-band GPS with SatIQ, and Garmin claims superior positioning accuracy. Maps depend on the lens: sapphire models come loaded with TopoActive maps, other versions have to download them, and Outdoor Maps+ is a paid subscription. It also has dynamic round-trip routing and NextFork.

Training tools

Ultra 3’s running metrics include cadence, stride length, ground contact time, vertical oscillation, running power, Race Route, Pacer and VO2 max, and the Action Button handles Precision Start. Cycling works with a Bluetooth power meter and Functional Threshold Power, and swimming tracks SWOLF, strokes and water temperature.

The fēnix 8 leans on Garmin’s coaching: training readiness, an endurance score, a hill score, PacePro and ClimbPro, plus strength plans that run about four to six weeks.

Diving, controls and light

Both hold EN 13319 certification for recreational dives to 40 meters. Ultra 3 is also water resistant to 100 meters under ISO 22810 and has a water-temperature sensor. The fēnix 8 is rated 10 ATM for water and has a 4 ATM dive rating, with scuba and apnea modes and leakproof metal buttons.

Ultra 3’s controls are the Action Button, the side button and the Digital Crown, plus double tap and wrist flick gestures. Holding the Action Button sounds a siren, and its flashlight is one of Apple’s safety features. The fēnix 8 has a dedicated LED flashlight with variable brightness, a red light and a strobe.

Apple rates Ultra 3 for use from minus 20 to 55 degrees Celsius on the wrist, 0 to 40 degrees in a dive, and altitudes from minus 500 to 9,000 meters.

Health tracking

Ultra 3 pairs Apple’s third-generation optical heart sensor with an electrical one, and it has the ECG and Blood Oxygen apps where Apple offers them. It measures wrist temperature, tracks sleep stages with a Sleep score, and can send sleep apnea notifications where available and hypertension notifications, the latter with age, pregnancy and region limits. It doesn’t have the Health Sensing System, which is on Ultra 4 and Series 12.

The fēnix 8 uses Garmin’s wrist heart rate. Its ECG app works in some regions for ages 22 and older, and Pulse Ox is a wrist reading that isn’t a medical device and isn’t offered everywhere. Sleep tracking includes advanced sleep monitoring, nap detection, a morning report with HRV Status, and Body Battery. Garmin doesn’t name a skin-temperature sensor. Neither Apple’s hypertension and sleep apnea alerts nor Garmin’s ECG and Pulse Ox readings are a diagnosis.

Price

Ultra 3 launched at $799 in the US in September 2025, with pre-orders from announcement day and stores from 19 September 2025, and it’s now the previous Ultra. If you’re paying close to that, Ultra 4 adds the Health Sensing System and a battery rated for 50 hours. Garmin’s suggested price for the fēnix 8 range started at $999.99 on 27 August 2024, and the finish, bezel and sapphire lens change it within the range, so confirm the exact model on garmin.com. Neither launch price is today’s street price; compare apple.com and garmin.com before you buy.