Both. The scale I got from amazon is an impedence device. I downloaded their app and it’s synched to the scale. I get a report on the app. Weight, BF, lbm, visceral fat, water, protein, bone mass and it calculates bmr. The scale at the gym is just a lot more expensive and theoretically more accurate. Again, I’m not overly concerned with absolute accuracy. I use the scale to measure relative accuracy. As long as I measure under the same conditions, the scale is pretty reliable.
That's cool, in the end I would probably love it. I did look into getting one, my wife would like it to sync with her phone.
But right now I have gotten a free read out from the Tanita tbf-300a scale at a health screening at the local senior center.
I have evolved into a kind of a bipolar luddite, we still have all tube TVs. But I do really like the fitbit gear 3, and since I was an digital data telecom engineer in MCI Communications, I had email since 1980 and a shed full of old electronics like a betamax video camera from 1983.
EDIT: It's actually a charge 3 fitbit watch.
But I decided that I need to upgrade both our our phones before getting anything that needs to sync, use bluetooth or otherwise use a smartphone. My smartphone is pretty clunky, an ASUS Zenpfone 2E with 1 gig ram, the reason I got it was it was totally free. I Had a flip phone on the old ATT network and ATT eliminate that network and offered the ASUS for free, no data plan pay as you go for ~$10 per month. I use a wifi hotspot at home for data, a lot of places have free hotspots, but I don't often use data away from home.
The fitbit app works, the ASUS bluetooth is a mite flaky, I can see it stop fairly often if I constantly monitor heart rate with the phone, or use a video endoscope. My wife's phone is better, but it's from Thailand and the specs on the bluetooth are finicky, things work on my phone but not hers.
So my plan, first I wanted to upgrade to something like two sumsung 9+ or galaxy s10 phones with a data plan, just looking around for the best deal and it isn't a current priority.
And all those BMI scales pretty much require a smart phone, one thing depends on the other.