When it comes to this device's basic functionality of counting steps and estimating distance, the HJA-301 is reasonably useful, as long as you take the time to calibrate it for your stride and walk or run at fairly consistent pace. However, it's easy to envision scenarios where your stride would vary enough to throw off the calculations, such as alternately walking and running, running uphill or downhill, etc. To be fair, I imagine most trackers suffer from similar shortcomings.
The HJA-301's additional functionality of counting calories, however, is completely useless. The reasons for this are that there are important factors that the device doesn't or simply can't take into account:
- It doesn't know whether you are running uphill or downhill.
- It can't take into account the fitness of the individual. Someone who is well-conditioned will burn fewer calories than someone of the exact same height, weight, and stride who is out of shape.
There are additional factors, but to put this into perspective, I did a hike with someone using a much more advanced calorie counter, and the HJA-301 reported that I burnt 1/4 the calories his device reported.
If all you want is something to count your steps and distance, I'd recommend picking up something cheaper or if you have a smart phone, spend a few bucks on an app. If you want something more advanced, look elsewhere.