Amazfit T-Rex 3 vs Garmin Instinct 3

Amazfit T-Rex 3 and Garmin Instinct 3 are watches released in 2024 and 2025, with overlapping phone compatibility. This comparison separates the catalog's listed specifications from missing information and approximate values. It covers 18 fields, including 12 exact differences; it does not choose a winner.

Specifications side by side

Field	Amazfit T-Rex 3	Garmin Instinct 3
Release year	2024	2025
Case sizes	48.5 mm	45 / 50 mm
Display	1.5-inch AMOLED 480x480	AMOLED or solar MIP (by variant)
Brightness	2000 nits	Not listed
Battery, as listed	Up to 27 days in regular mode · up to 40 days in saver mode	Up to 18 days (AMOLED) · unlimited (solar MIP)
Operating system	Zepp OS	Garmin OS
Phone compatibility	Android, iPhone	Android, iPhone
Cellular connection	None	None
Water rating	10ATM	10ATM
Glass	Gorilla Glass	Chemically hardened / sapphire (variant)
Case material	Stainless bezel, polymer frame	Reinforced polymer
GPS	Dual-frequency GNSS	Dual-frequency GNSS
Maps	Yes	No
Payment system	None listed	Garmin Pay
Plan requirement	Not required	Not required
Listed sensors and features	Heart rate, SpO2, Skin temperature	HRV, SpO2
Safety features	SOS calling	livelocate, SOS calling
Hardware flashlight	No	Yes

"Not listed" means the catalog has no usable value for that field. It does not mean the watch lacks the feature. Approximate values stay visible but do not support the difference count or numeric deltas.

Where they differ

Release year: Amazfit T-Rex 3 lists 2024; Garmin Instinct 3 lists 2025. The listed values are 1 years apart.
Case sizes: Amazfit T-Rex 3 lists 48.5 mm; Garmin Instinct 3 lists 45 / 50 mm. Keep the variant qualifications when comparing an individual model; this row describes the catalog entry rather than every configuration.
Display: Amazfit T-Rex 3 lists 1.5-inch AMOLED 480x480; Garmin Instinct 3 lists AMOLED or solar MIP (by variant).
Battery, as listed: Amazfit T-Rex 3 lists Up to 27 days in regular mode · up to 40 days in saver mode; Garmin Instinct 3 lists Up to 18 days (AMOLED) · unlimited (solar MIP). These are the full listed battery descriptions. Different modes or case variants prevent a single numeric battery-life delta.
Operating system: Amazfit T-Rex 3 lists Zepp OS; Garmin Instinct 3 lists Garmin OS. The listed software descriptions are not a guarantee of the software version currently installed on an individual watch.
Glass: Amazfit T-Rex 3 lists Gorilla Glass; Garmin Instinct 3 lists Chemically hardened / sapphire (variant). Keep the variant qualifications when comparing an individual model; this row describes the catalog entry rather than every configuration.
Case material: Amazfit T-Rex 3 lists Stainless bezel, polymer frame; Garmin Instinct 3 lists Reinforced polymer. Keep the variant qualifications when comparing an individual model; this row describes the catalog entry rather than every configuration.
Maps: Amazfit T-Rex 3 lists Yes; Garmin Instinct 3 lists No.
Payment system: Amazfit T-Rex 3 lists None listed; Garmin Instinct 3 lists Garmin Pay.
Listed sensors and features: Amazfit T-Rex 3 lists Heart rate, SpO2, Skin temperature; Garmin Instinct 3 lists HRV, SpO2. This compares the listed feature names, not measurement accuracy, clinical usefulness or availability in a particular country.
Safety features: Amazfit T-Rex 3 lists SOS calling; Garmin Instinct 3 lists livelocate, SOS calling.
Hardware flashlight: Amazfit T-Rex 3 lists No; Garmin Instinct 3 lists Yes.

What separates these two

Two 10ATM outdoor watches with military durability ratings, dual-band GNSS and SOS. The T-Rex 3 lists a 2,000-nit AMOLED display, offline maps, voice control and a skin temperature sensor; the Instinct 3 lists none of those four. The Instinct 3 answers with HRV tracking the T-Rex lacks, a flashlight, Garmin Pay, live location sharing, and the battery labels: up to 18 days on its AMOLED variant and an unlimited label on the solar MIP variant, while the T-Rex 3 lists up to 27 days in regular mode or up to 40 days in saver mode. The Instinct's display itself comes as AMOLED or solar MIP by variant.

Where they are the same

Both list phone compatibility: Android, iPhone.
Both list cellular connection: None.
Both list water rating: 10ATM.
Both list gps: Dual-frequency GNSS.
Both list plan requirement: Not required.

Which one fits you

Amazfit T-Rex 3 is listed as a watch compatible with Android, iPhone. Start with that phone requirement before comparing the other rows. The exact differences above are a way to identify which listed specifications matter to your use, not evidence that one model is better in every respect.

Garmin Instinct 3 is listed as a watch compatible with Android, iPhone. Start with that phone requirement before comparing the other rows. The exact differences above are a way to identify which listed specifications matter to your use, not evidence that one model is better in every respect.

Information is missing on at least one side for: Brightness. Those rows are excluded from the exact difference count.