S2 Body Fat not accurate

I've tried everything. Always 5-6% off. I posted here a comparative between Tanita, Withings and S2. The first 2 showed similar values but S2 always was off. Activity level 10 (Triathlete not pro). The BF% decreases that 5% only changing the age. Taking those 2 measures 1 min after the other, nothing else modified.

In addition. I'm not asking Garmin to lower my bodyfat%. Would be nice by the way :-)
With a large number of other athletes I ask to investigate and explain the difference in the measurement. Because I can imagine that the S2 is more accurate, more sensitive and therefore better than the S1. I only got whole numbers on the S1: 6.0%. The S2 already displays decimals: 17.4%. But side by side, a difference of 190%. Since the measurement seems consistent in my case, I think it has to do with algorithms. And if averages are used, then the question is whether the quite active athlete, including myself, falls into the average category?

The funny thing is that something similar is going on in the calculation of VO2max on the Garmin Forerunner 955. There is also something adapted, improved, to the algorithms so that it hardly moves or doesn't move anymore. No matter how focused you train. Now also being looked at and worked on..... I hope.

They remain estimates based on bioelectrical impedance. I use it as number and trend. For me the exact BF% is not very important. But I would like to know what is close to reality and where the difference comes from. In addition, it can have an impact on how someone deals with this! I trust my body and my gut feeling and run great marathons on it. There are groups that "rely" on this data and will act on it with perhaps nutrition, etc. But knowing Garmin, Garmin obviously wants to put down the best of the best! I think they will find a solution for it. Please Garmin let us know if you are still working on this?

• Consent to be added to an internal case - yes, I consent
• Consent to access your Garmin Connect account (if needed) -  yes, I consent
• What device/test are you comparing your Index readings to - Tanita BC 601
• What does your Index S2 display vs what does your reference device display -  S2 Fat = 19.3 Tanita =12.5
• What is your activity class set to, and is this appropriate for your activity level - 8 - Yes

Kevin, some news about new firmware? Garmin looks good with updating for fenix /epix series, but situation with smart scale is not respectable for this company like garmin.

I have returned Garmin Index S2 to the shop. The Garmin support told me, that Garmin know about issue and urgently work on fix. But they don't know if or when FW with fix will be available. If you look, when the first body fat issues on S2 Index were reported on forum, you find out, what word "urgently" means for the Garmin company.

Just got my S2 today, was shocked to see it say 16% when between tape measure and my old scale, I'm at 11%...and then I found this thread. FML. Debating returning it...or maybe getting an S1? I hear that the S1 was good and accurate?

So what are the tips to "tune" it so that it's closer? Change age down 20 years, and put activity level at 10?

I did that, it is then closer but might affect the vo2 max calculations 

Agree. I didn't change my age, but I do put it at activity level 10. I also weigh in around the same time every day and drink 3 cups of water before weighing in. Water seems to be the thing that throws it off the most. Lately my % of water has had big swings which then causes my body fat to change a lot from day to day. Yesterday my body fat was 13.3% with 63.3% water and today it was 13.9% with 62.9% water. Because of these types of swings, I think the best thing to do is use the weekly average. I don't like the daily swings, but it happens and the average is going to be a better indicator of actuals anyways.