Kospet’s Tank Ultra Watches Impressed Me a Little and Disappointed Me a Lot

Comfort and appearance

Tank M3 Ultra, left, and Tank T3 Ultra 2, right. Credit: Beth Skwarecki

These watches are huge. I will not count that against them, since they are clearly huge watches for people who want huge watches. If you want a huge watch, these deliver. If you want a heavy watch, definitely get the Special Edition that comes with a massive metal band. My god, it’s like walking around with a kettlebell strapped to your wrist. 

I prefer a small watch, so I’ve had to set aside my personal opinions and, in some cases, come up with workarounds to be sure a poor fit isn’t affecting the results of my testing. (More about that in the Accuracy section, below.) That said, you have to see what happened when I weighed these watches: 

• Tank T3 Ultra 2 (rectangle): 57 g without strap

• Tank T3 Ultra 2 with silicone strap: 78 g

• Tank M3 Ultra (round): 65 g without strap

• Tank M3 Ultra with silicone strap: 85 g

• Tank M3 Ultra with “special edition” metal strap: 149 g. That is one-third of a pound. There are ankle weights lighter than that! 

For comparison, a Forerunner 265 weighs 47 grams with its strap. The Apple Watch Series 10 that I have on hand (42 mm, the smaller of the two sizes Apple offers) weighs 38 grams with the sport loop strap. That’s right: one Kospet Tank Ultra watch, with its included strap, weighs more than two Apple Watches.

Apple Watch Series 10, 42 mm (top); Kospet Tank M3 Ultra, bottom. Credit: Beth Skwarecki

But, hey, if you want a large, tanky-looking watch, these fit the bill. They are metal, with little torx screws at the corners, and engraved labels telling you what the buttons do. The sides have thoughtful little indents and texture patterns—the kinds of things that can make a metal case feel premium. These definitely don’t come off as cheap and flimsy. I didn't personally do any durability testing, but Kospet says the watches are highly durable, with an IP69K rating for maximum dust-tightness and water resistance.

The silicone straps aren’t nearly so well-designed, though. They’re rubbery-feeling, and stretchy enough that the watch bounces around during a run. (Also, with six-inch wrists, I needed to use the smallest possible buckle hole, so anyone with smaller wrists may not be able to get a good fit at all.) Fortunately, both watches take standard 22-millimeter watch bands, so for everyday wear I swapped in the strap from a Garmin Forerunner 255, which is a little stiffer and has better adjustability. It also has a little nub on the keeper to stop the loose end of the strap from flapping around. If you get one of these Kospet watches, you’ll probably want to upgrade the band.

What it’s like to wear the Tanks

The interface for both Tank watches is simple and easy to navigate: 

• Swipe down from the top for a control center. There aren’t many icons, and it’s unclear what they do, but by adding them from the “More” menu and tapping them each in turn, you’ll figure it out. Awkward but not a problem once you get used to it.

• Swipe up from the bottom for your steps, heart rate, and other stats. This is the same stuff Garmin calls “glances” (I don’t know of a better term.) You can take measurements, such as blood pressure, directly from these tiles. 

• Swipe from the left to see your notifications. If you get any, that is. I had trouble with this. More on that below.

• Swipe from the right for apps. The app list is in a strange order—maybe it’s recents followed by an alphabetical list? But fortunately the icons are all labeled, and I didn’t have too much trouble finding everything I needed.

Both watches have a fitness tracking feature, available from one of the glances, that counts your calories, steps, and distance. On the M3 Ultra, these are displayed in much the same way as Apple’s fitness rings, despite using different data. (Apple's rings are calories, exercise minutes, and hours that you stood up at some point). On the T3 Ultra 2, they’re in a three-sector circle. 

Left: the M3 Ultra's fitness rings. Right: the T3 Ultra 2's fitness, uh, sectors? Credit: Beth Skwarecki

To turn on the watch’s display, you can press a button, or enable a raise-to-wake function. Unfortunately you cannot turn on the display by tapping the blank screen, which is what I’m used to doing with pretty much every other smartwatch. There is an always-on display (AOD) mode, but it drains battery. 

Apple Watch Series 10, left; Kospet Tank T3 Ultra 2, right. The Kospet isn't quite as bright as the Apple Watch in direct sunlight, but it's still readable. Credit: Beth Skwarecki

The watches don’t have an automatic brightness control. If you step outside on a sunny day, you’ll need to turn on the display, swipe down from the top, and tap the spot where you remember the brightness control being. Tapping it cycles through the brightness settings, and it can get nice and bright. You’ll have to turn it down manually when you go back indoors. On maximum brightness, in the sunlight, the Kospet watches roughly matched the visibility of the Garmin 265S and the Apple Watch. Maybe a tad dimmer, but definitely still readable. 

Charging and battery life

The charging cable and pins (both watches use the same charger) Credit: Beth Skwarecki

Kospet claims this watch has a long battery life, on par with Garmin's, but I found their estimates far too optimistic. The claimed 50 hours in “standby” mode doesn’t refer to regular smartwatch mode; when I commented to a Kospet rep that I was impressed by that number, they quickly qualified that standby is a specific low-power mode, not something you'd have on in everyday use. They clarified: “When used in smartwatch mode with features like continuous heart rate monitoring, GPS tracking, and other advanced functions, the battery life may be shorter, but it still performs impressively well compared to other devices on the market.” Kospet’s website claims 12 to 15 days for smartwatch mode. 

I didn’t find that to be the case, either. After taking the M3 Ultra off the charger at around 8 p.m. on a Tuesday, and using it for a bit under two days, including two tracked nights of sleep, it was at 67% by mid-morning Thursday. That’s about one-third of its battery life in two days, suggesting a six-day full-battery life. 

I didn’t even use the watch particularly heavily during that time. I took it for a run or two, and tried out the measurements like blood pressure and blood oxygen, but didn’t make any long phone calls, set health monitoring to continuous, or set the display to always-on. 

A six-day battery life is better than a typical Apple Watch or other smartwatch, and is about on par with a Fitbit Charge 6 or a Whoop. It’s nowhere near the typical life of a Garmin, with most of the Forerunner and Vivoactive models lasting 10 days or more. 

The charger is also disappointing. It’s a small magnetic charger whose magnets are so weak that you can’t really use the watch or move it around while charging, lest the charger lose its connection. The watch’s instructions say that you should run the battery down completely before charging it (tough to do if you want to always have enough juice to track a night’s sleep) and they also recommend leaving it on the charger for a full hour once it reaches 100%. 

Heart rate accuracy is terrible

These Kospet watches have the second-worst heart rate tracking I’ve seen on any device, and that’s a low bar since the worst was a pair of headphones that barely did the job at all. 

To test heart rate accuracy, I wear the watch I'm testing—either the T3 or M3 in this case—at the same time as a chest strap that measures heart rate electrically. Chest straps are the most accurate consumer-grade devices for measuring heart rate, and a good watch will show a heart rate graph that matches closely to the chest strap. I did several tests, sometimes with the M3 Ultra and sometimes with the T3 Ultra 2.

All gave nonsensical results, with the heart rate graph bouncing up and down but never or rarely matching what my heart rate actually was. Here are two representative runs, the top a Norwegian 4x4 and the bottom a steady run with some one-minute intervals in the middle. On all of these graphs, the chest strap for reference is in black, and the Kospet watch in pink:

Kospet in pink, chest strap in black. Credit: Beth Skwarecki

At first, I thought maybe this was just an issue with fit. After all, the watch is heavy, the strap is stretchy, and on my first run, the M3 Ultra was bouncing around so much that the skin over my wrist bone was pink and irritated when I came back from my run. I know from past testing that a poor fit (like wearing a too-big watch) can affect accuracy, so that was the first thing I addressed.

As I said, I’m not going to penalize these watches for their size. So I did another run using a compression sleeve to make sure the watch was snug against my arm, similar to the positioning of a Whoop bicep band or one of those arm band heart rate monitors. The heart rate readings were no better or worse, compared to wearing it on my wrist. Either way the heart rate numbers didn't match up with the heart rate chest strap, or with how I felt, or with the numbers I saw displayed during the run on a more reliable watch like my trusty Garmin.

The things I do for science. Credit: Beth Skwarecki

Before I wrote up my results, I had to consider that maybe I got a defective unit, or maybe the M3 and T3 would perform differently. So I did another set of tests with the T3 Ultra 2 (the round one), both on my wrist and on my bicep, and again got heart rate graphs that didn’t even come close to lining up with the data from my chest strap. In desperation, I grabbed my husband—who is often gracious enough to be my Large Man control group—and had him go for a run with the M3 Ultra on his wrist, using the watch band of his choice, which was the borrowed Garmin one. Once again, still terrible results.

Kospet in pink, chest strap in black. Credit: Beth Skwarecki

I wish I knew what was going on here. It sometimes looks like the data gets delayed or offset. Then again, maybe it’s just guessing. I asked the Kospet team if they were aware of any issues with the heart rate monitor or had advice for me. They gave me the standard advice of making sure the watch "is neither too tight nor too loose," and to check that my information in the app was correct. They also said, "The watch is an outdoor device and cannot be compared to professional medical equipment." Then they suggested I should focus my review on how durable the watch is. I'm sorry, but the durability doesn't matter if the watch can't do its job in the first place.

These two Kospet watches are simply not usable for any kind of heart rate training. If the sensor worked, I would need to point out some software issues with heart rate, including that you cannot customize your max heart rate or zones in the app, and that there’s a setting on by default that buzzes when your heart rate is above 150 (again, not a customizable number). But it's a moot point. This is not a fitness watch. Its heart rate tracking simply doesn’t work. 

GPS accuracy is surprisingly excellent

Kospet in pink, Garmin in black. Credit: Beth Skwarecki

Credit where it’s due: The location accuracy is excellent on these watches, and the compass and barometer/altimeter seem to be on par with my Garmin Forerunner 265S.  I took the watches running in a neighborhood with plenty of cul de sacs and right-angle turns, on multiple occasions, and the Kospet watches tracked my route nearly perfectly every time. Heck, I would have been impressed just at the fact that these watches have their own GPS, unlike many cheaper models of fitness tracker that simply copy your phone's location data. Having accurate dual-band is beyond my expectations.

Elevation profile during a run. Kospet in pink, Garmin Forerunner 265S in black. Credit: Beth Skwarecki

I wouldn’t normally bother testing the altimeter or compass on a basic fitness smartwatch, but as I was scrolling through the data from my runs, I noticed that the elevation profile from the Kospet watch closely matched that from my Garmin. Nice! Here’s the T3 Ultra 2 next to my Forerunner 265S, both showing the same compass headings, and similar altimeter readings. 

Garmin Forerunner 265S, left. Tank M3 Ultra, right. Credit: Beth Skwarecki

Barometer and altimeter both rely on pressure, so no watch will be able to get both of those data points totally correct without extra data (knowing your altitude and measuring pressure at that altitude, or vice versa). That’s why I’m not going to judge too harshly on the difference between, say, 941 and 1101 feet altitude. Something is working in there, and that’s more than most altimeter-less watches can say. 

Health features and measurements

I wasn’t expecting a blood pressure sensor; that’s something few wearables have. According to the scientific literature, it’s hard but maybe not impossible to get accurate blood pressure readings from a smartwatch optical sensor. The Samsung Galaxy Watch has a blood pressure feature, but requires it to be calibrated with a blood pressure cuff before you can rely on its measurements. The Kospet watches don’t have a calibration step.

On the Kospet Tank watches, though, blood pressure is just a feature that appears when you swipe up from the main watch face. You can measure it at any time. The readings I got seemed plausible, but I don’t have the ability to test this rigorously. I did compare to a wrist-based cuff like this one, and found that the readings were similar-ish, with the wrist cuff having more variation from reading to reading. Is the watch more reliable, or does it just pick a good guess and stick to it? I don’t have enough information to tell the difference. (Given the watches' performance on tracking exercise heart rate, I'm skeptical.)

Credit: Beth Skwarecki

The watches also do blood oxygen measurements. Mine were always between 97-99%, which is normal for healthy people—so again, this could be a measurement or it might just be a plausible guess. The watch can also measure “stress” (I’m at 39, “normal,” right now) and “emotion” (I’m “positive” and have recently been “calm”). Again, I can't validate these. They look cool, I guess?

App experience

Left to right: home screen with health metrics, watch face gallery, notification settings (I don't even have half these apps installed) Credit: Beth Skwarecki

The companion app for these watches is Kospet Fit (iOS, Android). It’s barebones, but has all the basic features a smartwatch app needs: It reports your steps, sleep, and so on. You can install new watch faces, including custom ones with a photo of your choice, and you can view a map and some summary details from each of your recent workouts. 

The app falls short in two major ways, though. One is that workout data can’t sync to Google Fit on Android (although it can sync to Apple Health on iPhones). I also can’t find a way to download raw data files (like .fit or .tcx) from the Kospet Fit app directly. Your only other option for syncing your workout data to another app is to link Kospet to Strava—which, pleasantly, works just fine. That’s how I got the files I needed to judge heart rate and GPS accuracy for this review. 

The other issue is important to anyone who cares about getting notifications on their smartwatch: There’s no way to get all your notifications. There’s a setting for whether you want phone notifications (like answering calls), and another for SMS notifications. Then, under a menu labeled “app notifications,” you can choose any or all of 19 specific apps. Wechat, Instagram, Facebook, and WhatsApp are all on there, but plenty of apps I use are not. There is a toggle for “other,” which sounds promising, but it doesn’t seem to work. 

In fact, I’m not sure if notifications are working at all. I’m pretty sure I got a text notification at some point, but right now my phone is full of notifications from texts, Signal, Instagram, Google Calendar, and various other apps. None of them have come through to the T3 Ultra 2 that I’m wearing. When I asked someone to call me, the watch showed a screen where I could answer the call, but it didn’t buzz or make any sound to get my attention. (That said, sound quality on calls is good.)

It’s buggy

Credit: Beth Skwarecki

The non-functional heart rate was the first reason I’m unable to recommend this watch. The incessant bugginess is the second. 

For example, notifications don't seem to work, as I described above. Sometimes data doesn’t sync from the watch to the app, and I have to refresh a few times to get it to show up. My battery level on one of the watches suddenly dropped to 10% when I was sure it should have been higher, and stayed at 10% for a few days. (In other words, I think the battery display was showing the wrong numbers.) 

I also had a problem with custom watch faces on both watches. I created a custom watch face with a photo of my kid’s art. Then I switched back to one of the stock faces. I can now see the custom face in my app, but can’t select it from the watch, and can’t sync it to the watch from the app. There's no way to get that custom face back. I tried on the other watch, with the same results.

I miss you already, custom watch face. Credit: Beth Skwarecki

I had some pairing issues, too. Each watch paired without much difficulty, but when I disconnected one watch to test the other, all of the sleep and workout data I’d recorded with the first watch disappeared from my app. I also woke up one night to a watch on my nightstand glowing brightly to ask if I’d like to delete all my data and pair to a different phone. (I think this is because I had paired it first to one phone and then to another, and it was homesick for the first one.) 

Credit: Beth Skwarecki

But the worst glitch of all was when all the text on the watch disappeared, and the icons turned into little squares made of lines. I could still view the watch face just fine (a very cool-looking golden dragon one) but all of the menus and dialogs were unusable. Restarting the watch didn’t help. After carefully comparing to my still-functioning watch (“swipe left, last item, second-to-last item, last item…”), I was able to select the right buttons to factory reset the watch. Still no dice. Finally I accepted a firmware update and the watch became functional again. Not fun! 

I asked my contact at Kospet about this, and they helpfully replied with a series of steps I could try to reset the watch. The steps were thorough: I could do it from the watch, from a phone that was paired to the watch, from a phone that was previously paired to the watch but currently isn't, and so on. If the team is as responsive to regular customers as to reviewers, that's a big point in their favor. (They have multiple ways to contact them on the website, and promise 24/7 support.) None of the reset steps would have helped me—I needed to do a reset and a firmware update—but I appreciate the thought.