Opening Suunto *.sml files with KubiosHRV

As you can read in my description, I am both a Software engineer and an endurance athlete. This combination results in the fact that I enjoy gathering and analyzing data of all my athletic endeavors.

For most of my activities, I use a GPS watch combined with a heart rate belt to ensure I train and race at the correct intensity. One of the many benefits of tracking heart rate data is the ability to analyze Heart Rate Variability (referred here as HRV) in order to avoid over-training. If you have never heard of it or if you would like to know more about it, I recommend the following article.

Ambit2Suunto Ambit2

The watch I use, a Suunto Ambit 2, allows me to record the R-R data (R-R is a synonym of HRV). Analyzed, this data can quickly tell me if I’m over-trained or not.

My protocol has been to measure my resting heart rate in bed when waking up. I measured it over a period of time, usually when I was peaking for a race. While Movescount (official Suunto website associated to any Suunto Device) allows anyone to see its R-R data for a given activity, it doesn’t offer a way to analyze the data. Who knows why?

RRMovescount It doesn’t look like I’m overtrained since it doesn’t look like anything!

Analyzing any R-R data is actually quite complicated and requires some very advanced mathematics (Digital Signal Processing algorithms). For this, I use a free software called KubiosHRV. You can find a great video tutorial on how to use this software here.

kubioshrvreport Example of KubiosHRV report

While KubiosHRV offers a quick & accurate way to analyze one’s HRV data, it can’t directly open a Suunto *.sml file (the Suunto ambit file format since 08/2014) to analyze the HRV data.

KubiosErrorError while opening a Suunto SML file

After playing around with Kubios, I found a way to fix this issue but it requires to modify by hand each SML file that you want to analyze.

I created a small tool to do this in batch: KubiosHRVDataFormatter (Download here 03/01/2017 UPDATE V2.0 AVAILABLE) will allow you to convert easily a given batch of Suunto SML files into a corresponding batch of xml files directly readable by KubiosHRV.



=> Open KubiosRVDataFormatter

=> Select the Suunto *.sml file(s) that you would like to convert

=> Specify the directory where you would like to have the converted Suunto files created

=> Open Kubios HRV and load your HRV data!



Let me know if you have any questions about the tool. As of today, it will only format the Suunto *.sml files but if you encounter the same issue with other file types, let me know and I can enhance the tool to convert them as well.

Notes: KubiosRVDataFormatter is compatible with Windows 7/8/8.1/10

9 thoughts on “Opening Suunto *.sml files with KubiosHRV

  1. I like the way you’re pushing the standard functionality here! I’m currently trying something similar with my Garmin data, although having difficulties with the varied intervals, as the HR data is attached to GPS data. Saying that, perhaps it would be good for me to disable GPS and see if there a constant interval to enable this analysis.

    Nice blog by the way!

    1. Thanks, I’m glad you liked it.
      Indeed, it can be tricky to determine the R-R intervals out of a file that only contains HR & GPS data. But it’s not impossible and it can be a good challenge!
      I would not think that it matters to have the GPS data. You can probably ignore it when parsing the file.
      Garmin does not offer R-R data within their watch ? Which model do you own ?

  2. Hi congrats for your blog.

    I have a problem, my movescount export KML files (from my Ambit3). How can I convert this type of file?


  3. Hi Frederic,

    actually I’m trying to convert kml files to use with kubios, to measure de HRV. I tried using firstbeat software, but it didn’t work as expected.

    If you have another options, please tell me something.


    1. Rafael,
      Sorry for my late answer.
      Could you send me an example of your kml files ? I will look at it and see if I can convert a kml file to be in KubiosFormat.
      If that works, I will add it to my KubiosHRVDataFormatter program


  4. Hello,
    Is the KubiosHRVDataFormatter still available?
    Does it transform sml to FIT?
    From Kubios HRV video it looks like they want the FIT file as input.

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