In the world of activity trackers, nothing comes close to the Mi Band's value. Cheaper than any Garmin or Fitbit tracker, even the most basic vivofit4 and Inspire, but still packing enough functionality, it also benefits from Xiaomi's name recognition and is considered a serious choice, not a cheap knock-off no-name tracker.

The most recent Mi Band 4 pushes the value-for-money envelop even further thanks to a colored AMOLED screen, swim tracking, and music controls, which get added on top of the previous generation's all-day activity, sleep, and heart rate tracking. Overall, the package is very attractive, but cracks are inevitably hiding below the surface, especially if you like spending your time in a pool.

The Good

Price $30-40 is cheap for what you get. Extremely cheap.
Display It's bright, visible outdoors, beautiful, and doesn't affect battery life much.
Battery life Even with auto-wake and heart rate measures every 30 minutes, plus some walks and swims, I can get about 10 days on a single charge.
Google Fit integration One of the few trackers that transfer weight measures, sleep, and activities to Fit.

The Not So Good

Interface It's not as customizable as I'd like. You can't reorder or hide exercise types, or remove unnecessary items from the More menu.
Android app Clunky and shows ads. It's sad that you get ads even after having purchased the band.
Swim tracking Worked well for the first two swims, then became completely unreliable.

Hardware, what's in the box

Xiaomi continues to use the same form factor in its Mi Bands: a small tracker that lodges firmly into a rubber band. No fancy clipping mechanism or band materials, the Band 4 is still as basic as it gets. The end result is understated — this isn't a band to wear to a formal dinner or your corner office job, but it's nothing to be ashamed of in casual settings.

The tracker is made of shiny black plastic, with the 0.95" touch display and home button on the front, and heart rate sensor plus two pogo charging pins on the back. The matte black rubber band uses a loop and clip mechanism. It's comfortable to wear and doesn't get unbuckled for no reason.

Compared to the Mi Band 3, the tracker is a little thicker and its top glass is less curved. The charging pins have moved from the bottom side to the back, but you still need to take the tracker out of the band to charge it, so there's no real benefit to this change.

 

Mi Band 3 (left) vs Mi Band 4 (right).

The most visible improvement is the beautiful AMOLED display. It's bright, crystal clear even in daylight, and can be adjusted to automatically lower its brightness at night. Functionally, it doesn't do anything new, but it looks gorgeous and I now find the Mi Band 3 old and cheap in comparison.

The display responds to swipes and touches, letting you swipe up/down through the different menus, tap to select, and swipe sideways or tap the sole button below it to go back. You can customize the order of the main menu items and hide some, but you have no control beyond that. For example, music controls are under More and there's no way to bring them up to the top level to make them more accessible. Edit: As pointed out in the comments, you can get to the music controls by swiping from left to right on the home screen. Another annoyance is that the six trackable exercise types are set in stone, so you can't remove one or put your favorite exercise first.

Those are a few examples of the limitations you start noticing with the Mi Band 4. It's cheap, capable, but also rudimentary in some ways. The packaging too is very basic, but that's fine. You get a regular carton box with the band, USB charging cradle, and manual. No fuss.

Setup and Android app

After installing the Mi Fit app and signing in with an account, you hit the + button on the top right and proceed to add your Mi Band 4. The process is fairly easy and quick, as long as the band is plugged into a power source and turned on.

Mi Fit is reminiscent of all of Xiaomi's software — tiny fonts, light grey icons and text, lots of unnecessarily wasted screen space, and weird UX decisions. You can't customize the home screen to show the metrics you care about, you can manually log sleep but not exercises (battery dead, forgot to wear the tracker), and you need two or three taps to see your day's workout(s).

Left: Home. Middle: Status (sleep, HR, weight). Right: My workouts (steps, workouts, calories).

Having used the app for nearly two months now, I still find it unintuitive in many cases. The main large card on the homescreen is one touch target, so tapping on sleep or heart rate or weight takes you to the same My status tab and not each corresponding data page. Another oddity is how each tracked metric's screen (sleep, HR, weight, steps, workouts, and calories) is organized. Some have a bottom tab to view their long-term history, the HR one doesn't. Some display a daily graph by default, but the workouts one starts with the weekly graph. Most have a daily/weekly/monthly view, but the resting HR is only available in a monthly view. Those inconsistencies are mostly aleatory and they're frustrating in everyday use when you tap, expecting to find an option somewhere, only to be disappointed that it's not.

Left two: Daily HR, monthly resting HR. Right two: Daily steps.

The one thing I did enjoy about the app are the added snippets below the sleep and steps graphs. They're very good at conveying stats in a clear way, explaining your averages, whether you fell asleep earlier or later than usual, slept more or less, and how you compare to similar users.

Left three: Daily sleep tracking screen. Right: Weekly sleep stats.

The app also has a Friends tab for socializing with other Mi Fit users, and a Profile tab where you can set goals and manage your Mi Band 4. Beside activity tracking, the band can be a bare-bones smartwatch, thanks to call, SMS, and app notifications, event reminders, and alarms. It can also vibrate and notify you when you've been idle for too long. More settings are available in the app for lift-to-wake (with daily schedule), heart rate detection intervals, night mode (lowers the screen's brightness), and auto-locking the band when you take it off.

Left: Profile tab. Middle & Right: Mi Band 4 settings.

This is also where you can download and set new designs for your band's display. There are about 50 different options, varying from simple digits to cartoons and popular characters. Unfortunately, the ones you save to your phone don't all get transferred to the band — only the currently chosen one is. So even though the band lets you pick between a few designs from its own menu, you just get 3 basic designs and the last one you sent from your phone. I wish I was able to save at least five designs on my band.

 

Left: Customizing the band's menu items. Middle & Right: Downloading new band displays.

Tracking with the Mi Band 4

I had been wearing the Mi Band 3 on one wrist and the Fitbit Alta HR on another for a few months, to double check how they compare. While the numbers were never the same between the two, they were awfully close, and that's stayed the same when I moved to the Band 4. Daily steps, heart rate (resting, during the day, during exercise), and sleep are 5-10% different from Fitbit's, a good sign. To me, the exact numbers don't matter as much as the overall trend, day after day. If my step count goes from 4000 to 4500, that's not important, but if it's up from 4000 to 8000, that's significant.

Mi Band 4 vs Fitbit Alta HR.

While passive tracking isn't something I worry about a lot, I'm much more interested in active tracking, especially now that I'm swimming again. That's actually one of the main reasons I bought the Mi Band 4 and why I was so excited to try it out.

Xiaomi took measures to avoid any wrong activations of the display with the water. After launching a swimming workout, the screen locks and requires a deliberate swipe up then down to view exercise stats, and then a long tap-and-hold on the home button to pause or stop tracking. In practice, it works well in the pool and I never noticed any weird vibrations or unwanted touches while swimming.

Left: Starting a swimming workout. Right: Stopping a swimming workout.

The first two times I swam with the Mi Band 4, I couldn't believe how good it was. I hadn't expected a cheap $35 (approx.) band to be this accurate at swim tracking, but it nailed the entire distance perfectly. That's even more surprising when you consider that I do an underwater flip at one end of the pool but take a breath at the other end, that I swim 9 lengths (225m) in freestyle then switch to a backstroke for the 10th length (25m), and that I take a super short break between each 250m round and do six in total (1500m).

Sadly though, every swim after that was completely wrong. One round (250m) became 427m or 479m, four rounds (1000m) became 1917m or 1979m, and so on. I even stopped all my shenanigans and tested a few continuous swims, all in freestyle and with underwater flips, no breaks, no backstroke, and still the results made absolutely no sense whatsoever. A hard reset and a manual choice of the length of the pool didn't help in fixing this.

The total distance isn't even a multiple of 25m, the pool length setting I choose, so did I swim to the middle of the pool, teleport to the edge, then stop the workout? And how 10 laps would yield a swim length that's not a multiple of 10 (929m) still baffles me. Something is clearly wrong with the hardware or with Xiaomi's algorithms.

Left & Middle: One proper tracked swim's stats. Right: When my swims stopped making sense.

Other types of exercises were thankfully more reliable. I tried walking, running, and going on a treadmill, and got the results I'd expected every time. For outdoor exercises, the Band 4 connects to your phone to get a GPS location. Also, during active workouts, the heart rate is measured more frequently than when idle so you get a more detailed graph and can see which parts were harder.

One short walk's stats.

Most of these tracked metrics can be synchronized with Google Fit. After establishing the link between the two services in the Mi Fit app, you should start seeing your logged weight, heart rate data, daily steps (divided in small chunks, like Mi shows them), and workouts in the Google Fit app. Syncing has been reliable for me recently, but there were a couple of weeks where it stopped completely (likely Google's fault). Also worth noting is that my tracked swims never made the jump over to Google Fit — not sure who's to blame.

Left two: Google Fit gets steps, sleep, heart rate. Right two: Also full exercise stats.

Should you buy it?

Yes. The Mi Band 4 is a no-brainer in terms of value for money. For an average price of $35-40 (depending on where in the world you buy it from), you get an all-day activity, sleep, and workout tracker, plus a few bells and whistles, like a nice AMOLED display, notifications, alarms, timers, and a stopwatch. You can also use the Band 4 to find your phone or the other way around, and sync your data with Google Fit. And all that can last about 10 days on a charge even if you enable lift-to-wake and the 30-minute interval heart rate monitor.

I do have a few reservations about the Band 4 though, and the main one is its swim tracking feature. Should it perform like it did for my first two swims, it'd be a brainless recommendation for casual swimmers like me, but in its current state, I can't endorse it for that.

Accessing music controls takes at least 2 swipes + 2 taps. Not practical if you're running or driving. Edit: But there's a faster way if you swipe from the left on the home screen.

The band and app's interface need to offer more personalization too. You should be able to hide workout types you never perform, save more than one custom display design to your band, get the app's homescreen to show the stats you care about, and you really shouldn't get ads in the app when you've already purchased the band. While these aren't minor quibbles, they don't detract from the main experience and can easily be fixed in future updates.

Buy it if:

  • You want a cheap activity tracker that does the basics right and offers minor smartwatch features
  • You want the best balance between battery life and features in your activity tracker

Don't buy it if:

  • You're a casual but regular swimmer
  • You care about floor counts — it doesn't have an altimeter
  • Price isn't an issue and you want the absolute best experience in your tracker — get a Fitbit Charge 3, Garmin vivosmart 4 or vivosport

Where to buy

  • Mi.com (check your local country's site)
  • Amazon.com ($45)
  • eBay ($30 and above, exercise your judgment when picking sellers)