Amazfit T-Rex review: $140 sport watch takes a bite at Garmin

The Amazfit T-Rex is the budget fitness company’s first outdoors smartwatch, and takes a direct shot at the Garmin sports watch market with a paltry $140 price tag.

The T-Rex is rugged, big, and boasts a far longer battery life than your Apple Watch or stylish Wear OS smartwatch.

It’s also a companion to the new Amazfit Bip S, which does a closer imitation of an Apple Watch and may be a better choice if you’re after something more basic – or just something not quite as hulking.

We’ve been living with the T-Rex to see how it compares to the Garmins and other outdoor watches of the world. Here’s our verdict.

Also consider: Fenix 6 | Garmin Instinct

Amazfit T-Rex: Design

Not quite as hulking as its namesake, Amazfit’s smartwatch is still no small affair. It comes in just one size – 47.7mm across and 13.5mm deep – and for women or anyone with smaller wrists, it's a real struggle to wear.

But at 58g it is at least mercifully light. The T-Rex is a mostly plastic affair that looks quite cheap put against a Garmin Forerunner or a Suunto. However, the stretchy silicone strap, budget as it may be, is incredibly comfortable to wear.

Huami says its watch has a “military-grade” MIL-STD-810G rating with 12 certifications to prove it, including heat resistance to 70 degrees celsius, cold resistance to -40 degrees celsius for 90 minutes, and humidity resistance to 240h. Put simply, this watch should be able to take a decent elemental thrashing and come out unscathed.

The display is an AMOLED that’s 1.3 inches across and protected by a Corning Gorilla Glass 3 with anti-fingerprint coating.

The T-Rex may only come in one size, but there are five colors to pick from: grey, black, khaki, “army green” and a white/green camouflage. All have the same white lettering and red accents adorning the front of the casing; there are four exposed screws between those, and four function buttons around the outside.

The watch uses a combination of buttons and touchscreen, and the responsiveness of both is good. That screen is also really vibrant with a 360 x 360 resolution, which makes the extended battery life all the more impressive.

It's not pretty, but if you covet Casio G-SHOCK chic, you're getting a lot of sports watch for $140.

Amazfit T-Rex: Fitness

Huami has really thrown the whole kit and kaboodle in here, including a heart rate sensor, a compass, and both GPS and GLONASS.

The Amazfit T-Rex is set up to track 14 different activities: running, treadmill, trail running, walking, elliptical, climbing, hiking, skiing, pool swimming, open water, triathlon, a generic “exercise” mode for the gym, and both outdoor and indoor cycling. And the rest of the time it will track your steps, heart rate and sleep.

We took the T-Rex for several workouts to see if it could keep up with a chest strap and other GPS devices, starting with a treadmill run.

Comparing the heart rate data against both a Polar chest strap H7 and an Apple Watch Series 5 on this 5K run, you can see that the T-Rex kept up during the steadier parts.

Amazfit T-Rex (above) vs Polar H7 chest strap (below)

During some two-minute intervals at the end, the T-Rex also didn’t do too badly, but overall it was slower to keep up with both the Apple Watch and the chest strap, often caught lagging 10 BPM or more behind in the live readout as our heart rate rose and dropped.

The final results were a little off, but not terribly. More concerning was this section of intervals, captured on a different outdoor run, where the T-Rex apparently either lost track or lost interest.

As you can see the T-Rex is quite off here, with the peaks and drops only vaguely resembling data from the chest strap, shown below. It wasn't the only case of this happening either. On another 5K outdoor run, we finished with some short intervals and the T-Rex clearly failed to keep up, registering 15 BPM lower than the chest strap during one peak.

So it’s fair to say the heart rate results are inconsistent. We've seen companies like Garmin make decent strides in this department, but Huami is clearly still lagging behind.

Thankfully, GPS performance proved a little better. Amazfit has recently had to release a patch to its watches to fix poor GPS accuracy, but fortunately there's no issues here on the T-Rex.

During an outdoor run where MapyMyRun was used for control, the final results differed by just 0.04 miles. Well within the acceptable margins for error.

We haven't been able to take the T-Rex hiking out in the wilderness, so we'll wait and see if the results are as good, but so far it's delivering on the GPS front.

It's just a shame the heart rate tracking clearly isn't up to scratch, despite improvements Huami has made to the sensor technology.

We’re going to keep using the watch, and we’ll update this review once we’ve done some longer-term testing with it to see if matters improve.

Amazfit T-Rex: Smartwatch features

So, let's talk about that UI. Huami is using its custom operating system here, which allows the watch to work nicely with both iPhones and Android devices. The main menu is accessed with a swipe to the left, while the left two buttons will scroll through your widgets.

The top-right button can also be configured to quick-access your most-used feature. By default this is set to starting an activity, but in the watch settings you can choose from a list of other options.

Naturally, the watch can also display messages and other notifications. The app will allow you to toggle notifications for a shortlist of individual apps such as Facebook Messenger and WhatsApp, but there's also an "Other" option that will allow all phone notifications to be mirrored on the watch.

Overall, the operating system feels more than a little similar to Wear OS, but that's fine by us. There are two clock faces to choose from on the watch right away, but jump into the companion app and there are heaps more to browse.

And to do anything with the T-Rex you'll need to download that smartphone app first. Confusingly, there are multiple Amazfit and Huami apps on the app stores, but the one you want is called Amazfit Watch.

Once downloaded and paired, we had to wait a good 15 minutes or so as it updated the firmware among other things.

The good news is that it's quite a comprehensive app once you're in, with the ability to drill down into the nitty gritty of workout data which includes graphs for heart rate, pace, altitude change, heart rate zones, and lap data. Some of these, like heart rate, can be selected for further examination too.

It's a far deeper experience than you'll get on Fitbit's app, for example, and more similar to Garmin's own, or the Polar Beat app that we regularly use to examine our EKG chest strap data (and very much like).

There are some granular settings on the T-Rex that we really like too. For example, you can set the times of day when lifting your wrist will turn on the screen, so you can ensure it doesn’t come alive and blind you during bedtime hours. You can even change how responsive that waking motion is.

On the other hand, there are some odd quirks and annoyances with both the watch and the phone app. Some hacked translations risk causing confusion, along with some style errors that all could presumably fixed with a quick edit sweep.

And while the UI is generally easy to navigate once you get the hang of it, there are some odd differences between the settings on the watch and those in the smartphone app.

For example, it took us ages to discover that enabling the raise-to-wake option was only accessible on the phone, yet quick-access settings must be configured on the watch.

We've no idea why it's divided up this way, and frankly it makes no sense.

Amazfit T-Rex: Battery life

One of the benefits of building these watches with cheaper materials is that they’re less battery-intensive, and battery life on the T-Rex is superb.

Huami says you should get 20 days of battery life with “daily use” (by its own definition: receiving up to 150 messages a day, activating the screen 30 times and running for 30 minutes every other day).

With GPS activated continuously, that drops down to 20 hours, which is still pretty impressive. And if you disconnect it from your phone entirely and switch off features such as heart rate monitoring, Huami says you’ll get 66 days – but you’re effectively just using it as a wristwatch at this point.

It's certainly giving Garmin a run for its money: the Fenix 6 lasts around two weeks when GPS is being used.

In our testing we tried out a variety of modes. After a treadmill run using just the heart rate sensor we’d barely burned off any battery at all. After 45 minutes of outdoor running, we'd shaved off only 5%. Impressive stuff.