Casio WSD-F21HR Pro Trek Smartwatch Review

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Wearable technology is the way of the future. The watch industry has quickly adapted with smart watch technology. Smart watches drastically increase your efficiency when you make use of all their features. The find my phone functionality will save you from wasting time looking for a phone that, after 30 minutes of searching, ended up being under a bedsheet.

The heart rate monitor will keep you from having to grip the metal slots on the treadmill in just the right way, in order to keep getting that biofeedback. This technology is the first stage in a drastic change toward how technology becomes more integrated with our bodies. With a technology that can augment our daily lives it is important to choose a smartwatch whose features integrate well with our lives.

First Look

The Casio Pro Trek WSD-F21HR Smartwatch is a sports watch through and through. This watch was designed with a more active and outdoorsy target market in mind. It’s integrated heart rate monitor that begins measuring your heart rate automatically if the watch detects motion.

Casio WSD-F21HR Pro Trek

The watch has a built in tool to measure oxygen consumption for your body per minute. It is rated at 5 bar WR meaning it can reach to 50 meters before suffering water ingress. The watch has a digital compass, altimeter, barometer, activity tracker and heart zone display. They are not trying to hide what kind of person this watch was designed for.


The Pro Trek WSD-F21HR is running the ‘Wear OS’ by Google. The OS used to be named ‘Android Wear’ because it is running a version of the Android operating system designed specifically for smart watches. Because the watch is running an Android OS it can pair up with your phone and integrate with your android phones ‘Google Assistant’. This works with the built in microphone on the watch. This also means your phones notifications can show up on your watch which makes checking for quick updates a lot more convenient. Plus you don’t look like a phone addict if you are only glancing down at your watch. For all you iPhone users out there you might check out the iMCO CoWatch.

Casio WSD-F21HR Pro Trek

The watch also integrates with GPS to provide on screen location information and the ability to create routes. You can find directions by voice command and view your agenda. The application integration is incredibly useful and even if you hadn’t thought of using a watch for such things in the past you will find yourself relying on it more and more as time goes by.


The display is obviously digital and measures 1.32 inches diagonally, with a resolution of 320×300. It is a dual layer display with a color TFT LCD and monochrome LCD. Naturally being a smart watch it is also a capacitive touchscreen that has anti-fouling coating. In more clear language, it is a very clear, bright, and crisp display. When out and about there was no difficulty viewing messages or other details on the screen even in full sunlight.

After getting the screen wet and just shaking it off the screen still had immediate response time. The screen also did not seem to have any noticeable changes in performance during durability testing on a dusty hike. The unique functionality in both the previous generation (Pro Trek WSD-F20) and the WSD-F21 is dual layer LCD and monochrome display.

The watch is able to switch between the color LCD and the monochrome LCD as needed in order to minimize power consumption and maximize lifespan. In monochrome mode you are able to display the time and various measurements that consume the least amount of power. The display is also quite easy to read in monochrome mode while in full light.

When you want to get the full smartwatch experience you can throw it over to the color LCD and display vibrant color maps, sensor output, and notifications.

Casio WSD-F21HR Pro Trek


The GPS color map display has a few interesting features. Clearly with any GPS you are able to display your current position. The useful hiking feature is that you can also display your recorded movement on a color map. While hiking it is much more convenient to view your GPS information without pulling your phone and out risking an unfortunate accident. You are able to set a trail on your phones display and then track your completion of that trail right on the watch.

The Pro Trek WSD-F21 also allows you to import GPS log data into the watch utilizing Google Drive. Another fun feature is showing routes you have already traveled and displaying markers you saved as checkpoints for interesting locations. An example of this is saving the location of some waterfall or hot spring or any interesting locations you find on your outdoor adventures.


The Pro Trek WSD-F21 has the classical diver and sport watch look. When you see the watch you know its meant to be a watch you wear while being physically active, and wearing the watch will indeed make you want to be physically active; If for nothing else than simply to make use of all the watches integrated features.

The watch comes with a urethane band in order to balance flexibility with durability. It has a double-pin buckle that aims to prevent any slippage and adjust the fit utilizing any of the dual holes found along the entire band. The holes are meant to be multipurpose allowing you to make those adjustments more easily but also to increase breathability so it doesn’t stick to your skin.

You will find resin used in the bezel of the watch. Here they aimed to make the watch as light as possible. The weight of the WSD-F21 coming in at 81g which makes it the lightest watch in the Pro Trek series.

Casio WSD-F21HR Pro Trek


We mentioned before that the WSD-F21 is water resistant up to 50 meters though Casio specifically states that it should not be used for diving or snorkeling. The resin in the bezel is definitely strong enough to protect the display from most bumps you will find yourself encountering often on a strenuous climb or hike. The band being urethane won’t be easily broken.

As a smart watch you always want to be a little careful with the screen itself however. Though the watch will survive the normal wear and tear or bumps and scrapes you encounter on a normal hike, I wouldn’t recommend rubbing the screen up against any rocks directly.

Despite that, you are still looking at a very solid MIL-STD-810 rating for durability. This is the United States Military Standard that tests everything a broad range of environmental factors such as high and low pressure, temperature shock, rain, humidity, sand, dust, fungus, gunfire vibration and a series of other tests. So with a MIL-STD-810 rating you can be fairly confident that your watch will survive most simple things you can throw at it.


The features of a smart watch are the meat and potatoes. Casio summarizes the watches features as ‘know your condition, know your location’. Clearly the condition side of this is all biofeedback related. The previously mentioned heart rate monitor is such an essential feature of the watch that the watch face links to the heart rate measurement functionality that automatically activates on motion. This motion can come in the form of walking, running, cycling or if the watch detects some type of gym activity. On heart data alone you get heart rate zone history, daily maximum and minimums, and of course current heart rate.

Casio WSD-F21HR Pro Trek

Another really cool feature is the V02 max. This actually measures your maximum oxygen consumption for your body per minute per kilogram of body weight. The data is meant to be used as a guide for endurance training helping you estimate your max running times as an example.

Among those features you also have a display of the calories burned for the current activity. The goal ETA for whatever preprogrammed fitness goals you configured are also displayed on screen. With that you can also see the remaining distance to goal, the heart rate graph, the altitude change graph and speed graphs. Pretty much all the data you could use to measure your performance.

Moment Setter

The moment setter feature of the watch is an app that allows you to configure an alert based on timing you specify. Essentially this is just a glorified reminder app with some additional features like automatically informing you of a coming sunset while you are working in the tracking activity app.

The app could be configured to remind you to drink in a workout or let you know how long you have traveled when it detects that you have stopped moving forward. This app is Casio’s attempt to make your feedback a bit more automated but there isn’t much more going on with the app.

Casio WSD-F21HR Pro Trek

Battery Life

The battery life is largely dependent on the use of the various apps and features on the watch. In ‘Multi-Timepiece Mode’ where only the time and sensor data are displayed with the monochrome LCD Casio advertises a 1 month battery life. Pretty solid but utilizing the watch in this mode non-stop makes the smart watch a not so smart watch.

With normal use of the smart watch features and in the color LCD mode you can expect about one and a half days of battery life. This naturally drops as you begin utilizing GPS or other biofeedback, alerting, or media functions on the phone. Considering you can switch between that power saving monochrome display and the color display you should be able to maximize your battery life by using the correct mode for the activity you find yourself engaged in.

Final Verdict

The Pro Trek WSD-F21 is a very solid sports watch. It is not a watch you wear to a dinner date by any means but when you throw on your hiking boots and want to pit yourself against the outdoors, it will serve you well.

5 thoughts on “Casio WSD-F21HR Pro Trek Smartwatch Review”

  1. Hi Techguru, I have a few questions about this model
    Can I receive calls?
    Can I pay using Google Pay?
    Can I install Nike run App?
    Can I download music using Google Play music?

    It is really hard to find this information

    Thank you very much in advance

  2. Hi Everyone,

    I would like to swap to this watch from fenix5.

    I have a few questions about this watch:
    – There is mobil application with this?
    – Can I GPS track my hiking trip?
    – If yes then can I download the gpx file?
    – Does it have website access for watch data (like garmin)?

    Thanks your answers!


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