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MobileIQ

Head to head

Apple Apple Watch Ultra 4 49mmvsGarmin Garmin fēnix 9 51mm

Released
2026-09-18Apple UK Newsroom — Apple Watch Ultra 4, retrieved 2026-09-13
Price
£749Apple UK store, retrieved 2026-09-13
Security updates until
Not published by the makerApple UK — watchOS 27 compatible models, retrieved 2026-09-22
Released
2026-08-25Garmin newsroom — fēnix 9 and fēnix 9 Pro, retrieved 2026-09-13
Price
£949.99Garmin UK store — fēnix 9 51 mm, retrieved 2026-09-22
Security updates until
2028-08-25Garmin UK — fēnix 9 (Security Information), retrieved 2026-09-22

0 wins for Apple Watch Ultra 4 49mm1 win for Garmin fēnix 9 51mm1 gap borderline1 difference you won’t notice£200.99 apart at RRP

Verdict: Garmin fēnix 9 51mm ahead on 1 row, Apple Watch Ultra 4 49mm on none

On the makers’ published figures, the Garmin fēnix 9 51mm wins on battery life (maker's claim) (696 h against 50 h). One gap is borderline, a difference most people would not notice: case size (49 mm against 51 mm). The difference in weight (case only) is below the threshold you would notice. The other 27 rows have no threshold or no direction to judge by, so nobody wins them.

Specifications

A win is marked only where the figures can be ranked and the gap is one you could notice on the wrist. A row the site has no threshold for says whether the two differ, and that it is not ranking them. = marks the same figure on both, ≠ not ranked a difference with no ranking. Every figure carries its source.

Body

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
Dimensions
49 x 44 x 12 mmOfficial
No verified data
Case size
49mmOfficial
51mmOfficial

Marginal — most people won’t notice.

Case shapeDiffers, but not ranked.
rectangularOfficial
roundOfficial
Weight (case only)
63gOfficial
65gOfficial

You won’t notice this difference.

Case material
TitaniumOfficial
No verified data
Water ratingDiffers, but not ranked.
Water resistance 100m (swim, snorkel, scuba, high-speed water sports) under ISO standard 22810:2010; EN13319 recreational scuba diving to 40mOfficial
10 ATM; 4 ATM Dive (EN 13319)Official

Display

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
Display typeDiffers, but not ranked.
Always-On Retina display with wide-angle OLEDs and LTPO3Official
AMOLEDOfficial
Display size
No verified data
1.4inOfficial
Display area
1245mm²Official
No verified data
Resolution
422 x 514Official
No verified data
Peak brightness
3000nitsOfficial
No verified data
Always-on display
YesOfficial
No verified data

Platform

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
Operating system
watchOS 27Official
No verified data
Chip
S11 SiPOfficial
No verified data
Storage
64GBOfficial
No verified data

Battery

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
Battery life (maker's claim)
50hOfficial
29 days (696 h)hOfficialwins this row

Garmin fēnix 9 51mm is ahead here, by a gap you’d notice.

Charge to 80%
45minOfficial
No verified data
Charging
Fast-charge capable, Apple Watch Magnetic Fast Charger to USB-C CableOfficial
No verified data

Health

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
SensorsDiffers, but not ranked.
Health Sensing System (third-generation electrical heart sensor, always-on optical heart sensor, blood oxygen sensor, temperature sensor), depth gauge, water temperature sensor, compass, always-on altimeter, high-g accelerometer, high dynamic range gyroscope, ambient light sensorOfficial
Garmin Elevate wrist heart rate monitor, Pulse Ox blood oxygen saturation monitor, barometric altimeter, compass, gyroscope, accelerometer, thermometer, ambient light sensor, depth sensor (to 40 m)Official
ECG
YesOfficial
No verified data
Blood oxygen
YesOfficial
No verified data
Skin temperature
YesOfficial
No verified data
GPSDiffers, but not ranked.
Precision dual-frequency GPS (GPS, Galileo, QZSS and BeiDou)Official
GPSOfficial

Connectivity

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
Cellular modelDiffers, but not ranked.
YesOfficial
NoOfficial
UK networks with eSIM
EE, Vodafone, Three3rd party
No verified data
Wi-Fi
Wi-Fi 4 (802.11n)Official
No verified data
Bluetooth
5.3Official
No verified data
NFC payments
YesOfficial
No verified data

Compatibility

SpecificationApple Watch Ultra 4 49mmGarmin fēnix 9 51mm
Works withDiffers, but not ranked.
iPhone 11 or later, including iPhone SE (2nd generation or later), with iOS 27 or laterOfficial
Compatible with iPhone and AndroidOfficial
CompatibilityDiffers, but not ranked.
iPhone onlyOfficial
iPhone and AndroidOfficial
5 attributes neither watch has a sourced figure for

Strap width · RAM · Battery capacity · Blood pressure · Cellular model price. Rows appear as sources are cited — a gap in our data, not a statement about either watch.

The pairs a buyer of either watch would also weigh. Any two watches in the catalogue can be compared from the chooser.