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Body Fat percentage wildly inaccurate, firmware algorithm update needed?

For a company that specializes in fitness and health related metrics, the Index S2 scale is an embarrassment. This morning my scales gave me a body fat percentage reading of 23.1%. This is me post work out a few hours later. Now I don't know what my actual body fat percentage is, but a look online at examples makes me fairly confident that I'm below 23.1% body fat, I'd even suspect more than 5% below, and it's said that impedance measurement can be plus or minus 5 percent. So the scales seem to be even less accurate than what would be considered the worst case scenario. Given the price of the scales, and that this is the kind of thing Garmin specialize in, it's an embarrassment. Will anything be done about it? And beyond keeping the surface of the scales clean, is there anything that can be done to try to improve the accuracy?

It seems to me that the algorithm is putting too much weight on BMI when trying to calculate body fat percentage, and that's making the measurements a complete waste of time and money.

  • Yeah, it would be nice if the algorithm added up to 100%.  However they want to slice that, a better explanation of each "measurement" (read: calculation based on age, gender, and weight) and exactly how the number is arrived at would be nice.  I want to understand why this scale thinks I'm obese.

    I really do wish someone from Garmin would get on here and give us some answers.  Maybe this is scale is only suitable for "average Americans," so overweight people?  Maybe they need to program a different algorithm for people who actually work out and care about being fit?  I don't know what the answer is, because I don't know the exact nature of the problem, but this scale has been extremely disappointing.

  • Just calc it yourself..  I don't have a scale myself.  but I doubt it's faulty to this "scale" 

  • I have, using several different formulas, several times.  It ranges from 22%-26%, depending on the formula.  I bought this specific scale so I wouldn't have to take a variety of tape measurements and plug those numbers into a formula!

  • ok I understand that I am just interested in buying one of those scales myself.

  • Right now I'd say DO NOT RECOMMEND.  This scale is supposed to use bioelectric impedance to MEASURE body fat % and other parameters, but it's pretty clear that only measures your weight and calculates everything else.  Disappointing. 

  • Soooo you have to tell the machine that measures your body fat %, what your body fat % is by using another machine that measures body fat %?

    That's stupid.

    I can understand it being a little out, and a proper fat test done to tweak the accuracy, but my S2 was telling me my body fat% was 23%!

    I had a VO2 Max Test done at a sports science lab and part of that was a proper fat% test using a machine, and then tested against a 7 skin fold caliper test. They were both saying my body fat% is cerca 11.5% which means my scales are very very off!

    Yes I set mine to athlete mode. Yes, I've now told the scales what my actual fat% is.

    Wish I'd not wasted my money on them tbh. Disappointing effort from Garmin

  • that is not calibration, it is a "fix" that garmin provided a few years after they released the scales so that you can tell it what to tell you back. in principle it gives them a baseline to measure changes from but in reality the scales don't seem to actually measure body fat in any meaningful way 

  • They said over 2 years ago that they were going to fix this. Hey Garmin, do better!

  • Well that seems to confirm what I thought. I'll probably get rid of my Garmin products sometime soon, hugely expensive and useless body composition scales, and the touch screen function on my Forerunner 955 stopped working a long time ago (yes touch is enabled).

    I'll be going with Coros Pace 3 next. *** of a lot cheaper and seems to do everything my Forerunner does.

  • Got a new Garmin scale and thought the %fat number it gave me was wrong because it was higher than my old Fitbit scale’s number. Went and got a DEXA scan and it turns out the Garmin scale was accurate.