Skip to content
MobileIQ

Head to head

Samsung Galaxy Watch Ultra 47mmvsSamsung Galaxy Watch8 40mm

Released
2025-07-25Samsung Newsroom UK — Galaxy Watch8 series, retrieved 2026-09-13
Security updates until
Not published by the makerSamsung UK — How to update software on Galaxy Watch, retrieved 2026-09-13
Released
2025-07-25Samsung Newsroom UK — Galaxy Watch8 series, retrieved 2026-09-13
Price
£319Samsung Newsroom UK — Galaxy Watch8 series, retrieved 2026-09-13
Security updates until
Not published by the makerSamsung UK — How to update software on Galaxy Watch, retrieved 2026-09-13

1 win for Galaxy Watch Ultra 47mm1 win for Galaxy Watch8 40mm0 differences you won’t notice

Verdict: Galaxy Watch Ultra 47mm ahead on 1 row, Galaxy Watch8 40mm on 1 row

On the makers’ published figures, the Galaxy Watch Ultra 47mm wins on battery life (maker's claim) (80 h against 40 h); the Galaxy Watch8 40mm wins on weight (case only) (30 g against 60.5 g). Both state the same peak brightness. The other 26 rows have no threshold or no direction to judge by, so nobody wins them.

True to scale

Galaxy Watch Ultra 47mm · 47.4 × 47.1 mmGalaxy Watch8 40mm · 42.7 × 40.4 mm

Case outlines from each maker’s published dimensions, drawn to scale. A round case is an ellipse at those figures.

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

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
DimensionsDiffers, but not ranked.
47.4 x 47.1 x 12.1 mmOfficial
42.7 x 40.4 x 8.6 mmOfficial
Case size
47mmOfficial
40mmOfficial
Case shapeSame.
roundOfficial
roundOfficial
Weight (case only)
60.5gOfficial
30gOfficialwins this row

Galaxy Watch8 40mm is ahead here, by a gap you’d notice.

Case materialDiffers, but not ranked.
TitaniumOfficial
Armor AluminiumOfficial
Water ratingDiffers, but not ranked.
10 ATM + IP68 + MIL-STD-810HOfficial
5 ATM + IP68 / MIL-STD-810HOfficial

Display

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
Display typeSame.
Super AMOLED, Full Colour Always On DisplayOfficial
Super AMOLED, Full Colour Always On DisplayOfficial
Display sizeDiffers, but not ranked.
1.47inOfficial
1.34inOfficial
ResolutionDiffers, but not ranked.
480 x 480Official
438 x 438Official
Peak brightnessSame.
3000nitsOfficial
3000nitsOfficial
Always-on displaySame.
YesOfficial
YesOfficial

Platform

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
Operating systemSame.
Wear OS 6Official
Wear OS 6Official
ChipSame.
Exynos W1000 (5 core, 3nm)Official
Exynos W1000 (5 core, 3nm)Official
StorageDiffers, but not ranked.
64GBOfficial
32GBOfficial
RAM
No verified data
2GB3rd party

Battery

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
Battery life (maker's claim)
80hOfficialwins this row
40hOfficial

Galaxy Watch Ultra 47mm is ahead here, by a gap you’d notice.

ChargingSame.
Fast Charging (WPC-based wireless charging)Official
Fast Charging (WPC-based wireless charging)Official

Health

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
SensorsDiffers, but not ranked.
Samsung BioActive Sensor (Optical Bio-signal Sensor + Electrical Heart Signal + Bioelectrical Impedance Analysis), Temperature Sensor, Accelerometer, Barometer, Gyro Sensor, Geomagnetic Sensor, Light Sensor, 3D Hall sensorOfficial
Accelerometer, Barometer, Bioelectrical Impedance Analysis Sensor, Electrical Heart Sensor, Gyro Sensor, Geomagnetic Sensor, Infrared Temperature Sensor, Light Sensor, Optical Heart Rate SensorOfficial
ECGSame.
YesOfficial
YesOfficial
Skin temperatureSame.
YesOfficial
YesOfficial
GPSSame.
L1+L5 Dual-Frequency GPS (GPS, Glonass, Beidou, Galileo)Official
L1+L5 Dual-Frequency GPS (GPS, Glonass, Beidou, Galileo)Official

Connectivity

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
Cellular modelSame.
YesOfficial
YesOfficial
Cellular model priceDiffers, but not ranked.
£599Official
£369Official
UK networks with eSIMSame.
EE, Vodafone3rd party
EE, Vodafone3rd party
Wi-Fi
No verified data
802.11a/b/g/n 2.4GHz+5GHzOfficial
BluetoothSame.
5.3Official
5.3Official
NFC paymentsSame.
YesOfficial
YesOfficial

Compatibility

SpecificationSamsung Galaxy Watch Ultra 47mmSamsung Galaxy Watch8 40mm
Works withSame.
Android 11.0 or higher and with more than 1.5GB of memoryOfficial
Android 11.0 or higher and with more than 1.5GB of memoryOfficial
CompatibilitySame.
Android; some features need a Samsung phoneOfficial
Android; some features need a Samsung phoneOfficial
6 attributes neither watch has a sourced figure for

Strap width · Display area · Battery capacity · Charge to 80% · Blood oxygen · Blood pressure. 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.