Autonomy, battery, actual use over several weeks
We read everything and anything about autonomy. “One month of intensive use”, “no need to recharge” – that’s storytelling. We’re going to stick to what holds up.
What the numbers show on the ground
Over four weeks of typical testing (3 running outings, 1 long hike per week, active notifications, sleep monitoring, activated screen on the wrist):
- T-Rex 3 Pro: recharges every 10 to 14 days in realistic use, with approximately 18–22% battery consumed on a 23 km / 1,150 m D+ hike in dual-band GPS.
- Fenix 8: recharge often spaced 14 to 18 days apart in the same conditions, with rather 14–18% battery consumed on this type of outing.
Both defend very well. The difference is that Garmin gives you finer tools to modulate your consumption (saving modes, screen management, battery profiles), where Amazfit mainly offers a large raw battery, less “controlled”, but very comfortable for the price.
On a daily basis: who tires the least?
Over a typical week of work, with around 5 hours of sport, both watches hold up without problem. You can go on trips for several days without the charger, as long as you don’t spend your life using GPS + maps + music.
The real difference comes when you go on big outings: the Garmin ecosystem gives you consistent graphics (load, recovery, fitness) and autonomy that fits well with what it advertises. Amazfit is improving, but there is sometimes a little dissonance between what the watch promises and what you see when you push it all the way.
Price, purchasing experience and final choice
This is the moment where you go from the “logical yes” to the final “big yes”. The one where you choose, and you assume.
Amazfit T-Rex 3 Pro: the smart premium
At around €399, often less during promotional periods, the Amazfit T-Rex 3 Pro offers a frankly aggressive package: titanium, sapphire, 10 ATM, 45 m diving, lamp, 180+ sports profiles, dual-band GPS, offline maps, large AMOLED screen. For someone who wants a real modern outdoor watch without going over the psychological bar of €400, it’s difficult to get more complete today.
If you’re coming from a simpler watch or an older T-Rex, the jump is huge. And for many, this will be more than enough, especially if you don’t live in the Garmin ecosystem in the first place.
Garmin Fenix 8: the work tool for obsessives
The Fenix 8 is more expensive, yes. But it sells something else: serenity. You pay for advanced mapping, the Garmin Connect ecosystem, sensor compatibility, and the rigor of metrics. You also pay for the fact that the majority of coaches, training plans and YouTube tutorials speak “Garmin” as a common language, which we see very clearly when we compare the Fenix 8 Pro to other behemoths like the Apple Ultra in my dedicated Fenix 8 Pro vs Apple Watch Ultra 3 comparison.
If you’re doing long trail, ultra, mountaineering or serious triathlon, the Fenix 8 isn’t just a gadget: it’s a real driving tool. There, the price is much more justified.
Clear recap to decide without lying to you
- “Strong sport + controlled budget” profile: Amazfit T-Rex 3 Pro. You get a lot for the price, with some software compromises.
- “Performance, mountain, long term” profile: Garmin Fenix 8. You pay more, but you know why every time you go out.
- You want LTE, satellite, MicroLED and everything else: you are clearly switching to the Fenix 8 Pro versions, which are still a notch above.
To further broaden the thinking on the Garmin side and see what alternatives exist in the same family, you can consult my commented selection of the best Garmin watches for demanding athletes.
