Polar M400 Activity Tracker Watch

I had a Chinese Mi activity tracker bracelet but I am also a watch wearer and I didn’t want to wear both a activity tracker bracelet and a watch (a G-shock) so I started looking for a activity tracker that could do both, to function as a watch and an activity tracker.

When I was shopping for an activity tracker watch, or a fitness watch, I was looking at something that would track steps as well as distance with a heart rate monitor. I bike and swim so I wanted to have GPS as well. My previous fitness watch is a Polar F7 so I also looked at Polar other than the Fitbits. The problem is that I do swim and Fitbit can’t go underwater and Jawbone doesn’t make any watches. I think the ideal watch for me would be the Polar V800 but I didn’t want to shell $350 plus for a fitness watch. The A300 is a nice sport watch but as a cyclist, the GPS is important to track my speed and distance. I just wish the M400 can actually sync to a HR monitor that could work in water while swimming. I decided to buy the M400.

I bought my M400 back in October of 2015 so I have been using it for about 8 months. So far I am satisfy with it. It does what it is suppose to do. I bought it for around $180 and it’s $199 included with tax. Now it’s actually only $157 so these things do drop their prices as time passes by.

So how do I like it so far? It does what it is suppose to do. It never broke down and the GPS worked well except maybe 2 days when it had a hard time finding GPS signal. One of them might has to do with it running out of memory.

I found out there is the trick to getting GPS started faster, it is to set it to your sport and the M400 will start to pick up the GPS signal, it takes about 10 seconds to 30 seconds usually, sometimes a minute or two. Then only then do you press record. Using this method you will not lose time when it is still looking for GPS signal while you are already on the move and it still looking for GPS signal because then it will suggest for you to standstill and wait which can take…forever sometimes. I used to just record it and let it find the GPS signal on the way while I am on the move and a few times it couldn’t or it only record part of the exercise.


I like the big screen of the M400. It’s very clear. It is simple to use. It’s totally waterproof so you don’t have to worry about going into the swimming pool or getting it wet. I haven’t try it at the sea yet but I would think it would be okay but you would have to rinse it with tap water afterwards. I really like how it would take me the time, heart beat, distance and average speed while I am riding on the bike clearly all on one speed. It’s big but I don’t find it bulky. I do take it off when I am doing some serious typing work on the computer, but it doesn’t get in the way of anything too much. I did scratch the screen though, so it would be good idea to buy a screen protector. The screen is plastic so it’s not hard or scratch resistant. The bluetooth HR monitor that came with it works well and never missed a beat. Overall, it’s what you expected with Polar, a very well established brand in the fitness equipment business. The M400 is reliable and I really like how I only have to charge it once every two weeks or so depends on how much I use the GPS. It would probably last 3 to 4 weeks if you are not using the GPS at all.

However, with the GPS on, the battery life is only about 8 hours maximum, mine drained out at around 5-6 hours but it wasn’t fully and newly charged that day. I was already wearing it for a few days before I went hiking with the GPS on the whole time to track my progress.

It did drain out on me when I went for a whole day cycling but the great thing about the M400 is that it uses the very common mini USB port which is basically the one all Android phones use so you can easily give it a quick charge with your external battery pack. You can charge it up to about 70% in about 45 minutes so you could basically charge it up during lunch or during rest easily.

Now I am going talk about some of the things the M400 doesn’t do quite well on.


Weak Sleep Data

The Polar M400 doesn’t really track sleep. There’s no data for sleep and it’s quite disappointing such a high-tech product.


Heart rate monitor doesn’t work in water

One major disappointment for me is that the HR monitor chest band doesn’t work in water so it won’t track heart rate while swimming. This is something that kind of baffles me because I also own the Polar F7 and the HR monitor works in water and I use it in the pool with me, so why can’t a newer and more high-tech model doesn’t work in water.


Skin irritation

I am someone, one of those freaks, who wears the watch the whole day and night even in shower and sleep. I wear my watch 24/7 until I found that the soft comfortable band was making my skin look dry and red. It wasn’t itchy but the skin on my wrist was certainly has an issue with it. After that, I put it on my right wrist and it would happen to skin of my right wrist after a week or so. Afterwards I decided to take it off at night to give my skin a breather. It was better.



Overall, the Polar M400 is a very good product and function well as a GPS fitness watch. I don’t regret buying it and it has served me faithfully in the past 8 months. I just wish it tracks more sleep data, has a HR monitor that works in water for swimming and the issue with skin irritation. I hope Polar can come up with software update or new product that would solve those issue because the M400 is good but it just miss some marks to prevent it from being a great all-around product that can truly do multi-sport like its much more expensive sibling, the V800 which cost more than twice as much. I find it frustrating how M400 is fully waterproof yet it cannot receive analog signal from the H7 HR monitor in water. It’s just weird because the V800 uses the same H7 HR monitor strap. I really hope a software update could change that, but it is probably a hardware thing where the M400 just doesn’t have the sensor to receive the analog signal from H7.

So maybe I will get the V800 or another one later when the M400 has served its time.