[Overwhelming toughness gives you peace of mind] No problem even running on snowy roads in Hokkaido in the middle of winter! The Amazfit T-Rex Ultra is military-grade tough

Wednesday, July 10, 2024

Written by Saito Titoce

We have introduced the Amazfit T-Rex Ultra, a smartwatch boasting the world's highest level of toughness. It has passed 15 rigorous tests known as the MIL standard, can withstand scorching temperatures of 70 degrees, operates at -30 degrees, and is suitable for free diving at depths of 30 meters. We would like to share the results with you

table of contents

What is the Amazfit T-Rex Ultra, the world's toughest smartwatch?
Detailed Review
Summary: The Amazfit T-Rex Ultra is not over-specced at all
Amazfit T-Rex Ultra details and purchase information

What is the Amazfit T-Rex Ultra, the world's toughest smartwatch?

The Amazfit T-Rex Ultra boasts the world's highest level of toughness. Its design is not as delicate as other smartwatches, but rather feels quite sturdy

Amazfit's rugged smartwatch, developed by Zepp Health Corporation

When you hear about the Amazfit T-Rex Ultra, a smartwatch that boasts the world's highest level of toughness, many people will wonder, "What manufacturer and brand is that smartwatch from?"

"Amazfit" is a brand of smart wearable devices developed in September 2015 by Zepp Health Corporation, a company headquartered in Hefei, China, with operations in the US and based in Cupertino, California. In the third quarter of 2022, it recorded the third highest number of shipments in Japan

Amazfit is currently a globally expanding smartwatch brand, and the toughest and most outdoor-friendly smartwatch from the Amazfit brand is the Amazfit T-Rex Ultra

First of all, in terms of toughness, making it suitable for outdoor use, it has passed 15 military-grade MIL-standard tests, including shock and humidity tests, and can withstand temperatures ranging from scorching 70 degrees to extreme cold of -40 degrees, function properly even in harsh environments of -30 degrees, and is water-resistant to a maximum of 100 meters.It is also certified to EN13319 and ISO 6245, the international standards for diving accessories, and is suitable for free diving up to 30 meters

The body is made of 316L stainless steel, which is durable and corrosion-resistant and is also used for medical scalpels and scissors.It also features a patented mud-proof bridge and buttons that protect the body from dirt and debris, making it one of the toughest watches not only as a smartwatch but also as a regular wristwatch

The back cover of the Amazfit T-Rex Ultra, which is equipped with various sensors, shows that the back is also quite robust

The Amazfit T-Rex Ultra also boasts powerful smartwatch functionality, including dual-band positioning using both L1 and L5 signals, a powerful GPS function that supports six satellite systems, and an offline map function that displays downloaded maps on the Amazfit T-Rex Ultra

It's equipped with a wide range of sensors, allowing it to measure heart rate, blood oxygen levels, stress levels, breathing rhythm, and more, and can also record exercise and sleep levels. It also has a feature called Zepp Coach, which uses AI to provide training plans and guidance, making it a smartwatch well-suited for daily exercise management

Outdoor features include compass, barometer, altimeter, altitude assistant, altitude blood oxygen level reminder, sun and moon rise and set, tide, storm alerts, and water temperature for freediving

With so many features, you might be concerned about power and battery life, but the battery has plenty of capacity, with up to 20 days of continuous use under standard use, 9 days under hard use, 25 days in power-saving mode, 80 hours in long-battery GPS mode, 28 hours in high-precision GPS mode, and 58 hours in power-saving GPS mode

The Amazfit T-Rex Ultra is extremely tough and multifunctional, and its market price as of July 2024 is just 59,900 yen, making it a great value for money. I personally tried out this outdoor smartwatch.

Recommended points

Overwhelming toughness that you don't have to worry about doing anything
Cold resistance that guarantees operation even at temperatures as low as -30°C
Heat resistant up to +70 degrees Celsius, which is scorching hot
Water resistant for free diving up to 30m
High basic performance as a smartwatch

Points of interest

It weighs only 89g, but it feels surprisingly heavy and large
It has so many functions that it's hard to decide how to use it in conjunction with a smartphone

Main specifications and evaluation

item	Amazfit T-Rex Ultra
Outdoor Gearzine Review
design	★★★★☆
toughness	★★★★★
Cold resistance	★★★★★
Operability	★★★★☆
Long-lasting operation	★★★★☆
Cost performance	★★★★☆

■Design

Color: Abyss Black/Sahara
Size: 47.3 x 47.3 x 13.45 mm (excluding heart rate base)
Weight: 89g (including band) / 61g (excluding band)
Body Material: Stainless steel (bezel, back panel, bridge, buttons), polymer alloy (middle frame)
4 buttons
Waterproof grade 10ATM

■Display

Display material: AMOLED
Display size: 1.39 inches
Resolution 454×454
PPI 326
Touchscreen glass material + anti-fingerprint coating

■Band

Band Material: Silicone
Band length 140mm to 205mm
Band width: 22mm
Band specifications: Classic pin buckle

■Battery

Battery capacity: 500 mAh (typical value)
Charging method: Magnetic charger
Charging time: Approximately 2 hours
Sports Features

■ Health function

24-hour monitoring of heart rate, blood oxygen level, and stress level
Manual measurement: Heart rate/Blood oxygen level/Stress level/Respiration rate/One tap measurement
Sleep quality monitoring Sleep stages (including REM) Nap time/Sleep schedule/Sleep breathing quality/Sleep score
Health Assessment System PAI
Breathing exercises: Yes
Menstrual cycle tracking: Yes
Health Reminders Abnormal Heart Rate/Hypoxemia/High Stress Level/Breathing Exercises/Sedentary Reminders

■Sensor

Health BioTracker™ PPG biosensor (for blood oxygen)
Movement Accelerometer, Gyro sensor, Geomagnetic sensor, Barometric altimeter, Ambient light sensor
Connection: Bluetooth 5.0 BLE / WLAN 2.4GHz
Positioning system: Dual band & 6-satellite positioning (GPS, GLONASS, GALILEO, BDS, QZSS, NavIC) *Indoor location services are not supported
Motor Linear Motor

■Other

Speakers: None
No microphone
Mini app compatible *Some Japanese not supported
Alexa (Japanese support) No
Offline voice assistant: No
Sleep mode: Yes
120+ watch faces (including over 10 animations)
Music storage 2.3GB
App Zepp app *Not compatible with tablets
OS: Zepp OS 2.0
Supported devices: Android 7.0 or later, iOS 12.0 or later
Set contents: Smartwatch (including genuine band), dedicated charger, instruction manual

Detailed Review

My regular smartwatch gave up during a winter run in Hokkaido

If you exercise regularly, most people are probably now using a smartwatch to record their exercise in detail

As already mentioned, the Amazfit T-Rex Ultra is arguably the world's toughest smartwatch, but even as an outdoor enthusiast living in Hokkaido who often takes photography trips in a camper van and writes reviews of camping gear, I felt that there were very few situations in which the level of toughness of the Amazfit T-Rex Ultra would be necessary

In other words, I liked the rugged design with an outdoor feel, and I thought that the overwhelming sense of security and joy of ownership were the main reasons for buying a watch. Even if you bought a submariner-type watch that was waterproof to 200 atmospheres (200m), as has been the case in the past, no one would actually dive 200m, and even if it still worked after sinking to the bottom of the ocean 200m deep, there would be no way to retrieve it, so I thought that it was an unrealistic spec

However, I quickly found myself reaching the limits of the Amazfit T-Rex Ultra. It was a bolt from the blue. I wear a smartwatch when I run, hike in the woods or mountains, or go outdoors. I aim to run every day, even in Hokkaido's winter, and when I did, my standard smartwatch stopped working

Zepp Coach is an exercise coaching system that uses AI to create training schedules tailored to your preferences and schedules

I didn't do my research properly, but it's true that in Chitose, Hokkaido, where I live, temperatures can drop below -20°C in the early mornings in the middle of winter, but there's no need to run during the coldest hours. Therefore, I thought that even though it was cold during the time I was running, it would be around -10°C, not cold enough to cause my smartwatch to stop working

However, the Apple Watch explanation page on the official Apple website , I found the following statement:

■ Recommended conditions for use and storage for most Apple Watch models

Apple Watch is designed to work comfortably in temperatures between 32°F and 95°F (0°C and 35°C)
The ideal temperature range for storing your Apple Watch is between -4°F and 113°F (-20°C and 45°C)

■ Recommended conditions for using and storing your Apple Watch Ultra

Apple Watch Ultra and later works well under the following conditions:
Wear Apple Watch Ultra in temperatures between -4°F and 130°F (-20°C and 55°C)
Apple Watch Ultra charging temperature: 32°F to 95°F (0°C to 35°C)
Apple Watch Ultra storage temperature: -4°F to 113°F (-20°C to 45°C)
Water temperature during water activities with Apple Watch Ultra: 32°F to 104°F (0°C to 40°C)
Relative humidity: 5% to 90% (non-condensing)

As shown above, the temperature I consider normal for my daily life was already above the operating temperature of a typical smartwatch. As a result, my smartwatch stopped working while I was running, and I was unable to accurately record my run that day

"Amazfit T-Rex Ultra" is easy to use for everyday running

You can specify and record various types of exercise in detail, such as "running (outdoors)," "trail running," and "walking."

Personally, the Amazfit T-Rex Ultra's specs, which allow it to withstand temperatures as high as 70 degrees and function accurately even at -30 degrees, are mostly about the peace of mind and joy of owning it, and I didn't think I would use a smartwatch solely for its performance. However, as someone living in Hokkaido, I really needed the toughness of the Amazfit T-Rex Ultra when running on cold winter days

Perhaps because I run while checking my time, pace, heart rate, etc. on my smartwatch, the watch face is exposed and not hidden by my sleeves, and I swing my arms, making the cold even more severe. However, since switching to the Amazfit T-Rex Ultra, my smartwatch never stopped working while running in Hokkaido. Incidentally, I also wore it on a trip to Harbin, China, where it's even colder, and there were no problems there either

By checking the details of the exercise record recorded under "Exercise" in the "Zepp" app on your smartphone, you can see in detail changes in your "heart rate" and "pace" during exercise

The Amazfit T-Rex Ultra also has exercise management features such as "exercise" and "exercise record." Using the Zepp smartphone app, you can check your running progress in detail, including pace, heart rate, real-time performance, power, altitude, gradient distribution, cadence, stride, training effect, and details for each kilometer, allowing you to objectively review your running. It's great that you can check not only simple things like whether your time is improving, but also cadence (steps per minute) and stride (step length), allowing you to see changes in your running data

The Amazfit T-Rex Ultra also supports an offline map function that allows you to use downloaded map data offline, so you can check the map on the Amazfit T-Rex Ultra alone. However, in my case, there is a function in the Zepp smartphone app that displays the locations of my runs on a map in the exercise records, which I find very enjoyable as I can review the locations and courses I ran on later

The "Maps" function allows you to use detailed map data offline. If you can use it effectively in conjunction with the map on your smartphone, it will be even more useful

It also comes with an AI-powered "Zepp Coach" function that manages things like your training schedule and fatigue levels, making it a very interesting feature for those who love running and exercise. Depending on the settings, some may suit you better than others, so we recommend fine-tuning this part

For me, the Amazfit T-Rex Ultra offers extremely high performance as a smartwatch for running, but when considering it as a smartwatch for running, the fact that it is a little large and heavy is a concern, although this is understandable due to issues such as durability

A variety of useful functions for outdoor use

The "compass" function is one that I use more often than I expected when taking photos. It is extremely useful for predicting the positions of the sun and moon

The Amazfit T-Rex Ultra works perfectly as a smartwatch for everyday running, but it also comes with plenty of outdoor features, making it perfect for photography trips in a camper van

For example, the "Compass" function is very useful for me as a photographer. I often use it in combination with the "Sun and Moon" function of the same "Amazfit T-Rex Ultra." First, I check the sunrise and sunset times with "Sun and Moon," and then I use the "Compass" to check in which direction the sunset or sunrise will appear

Using the "Sun and Moon" feature on the "Amazfit T-Rex Ultra," you can easily check not only the rising and setting of the sun, as shown in the photo, but also the rising and setting of the moon and the tides

When I use a multi-function smartwatch like the Amazfit T-Rex Ultra, I often wonder how much of it I should use on the smartwatch. In many cases, anything a smartwatch can do can also be done on a smartphone. And when wearing a smartwatch, the smartphone is usually in a jacket pocket or somewhere similar

So, while smartwatches have an overwhelming advantage when it comes to checking your running pace and heart rate, smartphones are often more convenient for checking a map while walking due to their screen size and ease of use. A smartwatch is sufficient for checking your direction and the sunset and sunrise times, but if you have the time, it's also a good idea to check it on your smartphone and plan your trip more carefully

The Amazfit T-Rex Ultra also has storage capacity for music data. Deciding whether to store music data on your smartphone or the Amazfit T-Rex Ultra can be a difficult decision

Even when listening to music using Bluetooth earphones, there's the question of whether to link it to your smartphone or your smartwatch. In that sense, I still tend to be smartphone-centric. However, as the difficulty of mountain climbing increases, not just running, I'll likely rely on my smartwatch for checking maps and other things. In that sense, the Amazfit T-Rex Ultra, which supports offline maps and music downloads, is a great ally

The decision of whether to use a smartwatch or a smartphone may be a matter of personal preference. In any case, the Amazfit T-Rex Ultra combines impressive toughness with the high performance of a smartwatch, making it an extremely reliable piece of outdoor gear

Summary: The Amazfit T-Rex Ultra is not over-specced at all

If you plan on skiing or snowboarding, a cold-resistant smartwatch is a must

I've found myself using the "Find My Smartphone" feature far more than I expected. It simply vibrates the paired smartphone, but it's incredibly convenient

What surprised me when I actually used the Amazfit T-Rex Ultra this time was that the recommended operating temperature range for a typical smartwatch is much narrower than I thought. Even the relatively expensive Apple Watch has a recommended operating temperature range of around 0 to 35 degrees, so even slightly cold places are outside the recommended operating range

In Hokkaido, where I live, it's not uncommon for temperatures to drop below zero even on flat land in December, but this is still outside the recommended operating temperature. In fact, I've never heard of anyone using an Apple Watch in Hokkaido having it stop due to the cold, so it probably doesn't stop working that often. However, for people like me who like to run in the middle of winter, or who like to do outdoor activities like camping, mountain climbing, skiing, and snowboarding, it seems like a typical smartwatch that isn't cold-resistant doesn't have the specs to last

Smartwatches are generally more vulnerable to cold than people think, so if you're active in cold regions, be sure to check this point before purchasing. Smartwatches like the Amazfit T-Rex Ultra can withstand extreme cold temperatures from -40 to 70 degrees and operate accurately even at -30 degrees, making them extremely reliable for outdoor enthusiasts as they have practical specs rather than boastful specs. Why not consider it as one of your potential purchases?

Another feature of the Amazfit T-Rex Ultra that I found surprisingly useful was the "Find My Smartphone" feature. It's a simple feature that makes the paired smartphone vibrate when activated, but it's useful when you lose your smartphone in the camper

Amazfit T-Rex Ultra 47mm Smartwatch for Diving and Outdoor Activities, Features Map Display, Navigation, GPS, Mudproof, AI, Ultra-Low Temperature Operation, Waterproof, Blood Oxygen Monitoring, Sleep Monitoring, Line Notifications, and Incoming Call Notifications, Round Design

created by Rinker

¥49,900 (as of 2026/02/07 11:31:29, according to Rakuten Market - Details)

Amazfit T-Rex Ultra details and purchase information

For more product information, please visit the Amazfit official website

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Chitose Saito

A former editor of a monthly camera magazine, he became immersed in the outdoor lifestyle of campervans and car camping while pursuing Hokkaido's spectacular scenery and wildlife. He is currently a photographer and writer who travels all over Hokkaido with his wife and two-year-old son, capturing and writing about everything he experiences, from cameras and lenses to outdoor activities, camping, child-rearing, PC gadgets, cooking, and even dieting. For OUTDOOR GEARZINE, he plans to write a variety of articles, primarily for the "QOCL (Quality of camping life) Improvement Committee," which aims to improve the quality of life while camping and in a campervan

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