10-21-2014 07:08
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

10-21-2014 07:08
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
I opened my account yesterday, entered weight, but do not know how to calculate my % body fat. Can someone help me with this please.
10-21-2014 07:52
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

10-21-2014 07:52
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
11-04-2014 17:09
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

11-04-2014 17:09
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
Most people use a scale that calculates the body fat percentage for you. Fitbit's Aria scale is one of the many that will do that. These scales are not perfectly accurate, but they do give you an idea of how your body is trending over time. I think that the only truly accurate way of measuring body fat percentage is through a trainer at a gym or a doctor (unless someone out in fitbit land knows another way to do it.) Keep in mind that the BMI (body mass index) doesn't measure fat, it only compares your weight to your height in a very rough estimate of how much you should weigh for your height. Good luck!
11-04-2014 18:06
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

11-04-2014 18:06
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Actually, that BMI calculator that MidnightShadow linked to does have some sort of BF% calculator that works from weight and waist, wrist, forearm and hip measurements - how accurate is it? I don't know. FWIW, my Tanita scale says my BF% is ~7% and this thing says ~13%, quite a difference.

11-04-2014 22:24
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

11-04-2014 22:24
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
This gives average of several calculations.
Figure that a bunch of potentially 5% accurate calc's can improve the estimate.
http://www.gymgoal.com/dtool_fat.html
Help the next searcher of answers, mark a reply as Solved if it was, or a thumbs up if it was a good idea too.

09-08-2017 04:45
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

09-08-2017 04:45
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
how do I calculate bmi and lean-to-fat content?
@tiredmama wrote:I opened my account yesterday, entered weight, but do not know how to calculate my % body fat. Can someone help me with this please.
09-08-2017 05:32
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post


09-08-2017 05:32
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
@Lindamattila wrote:how do I calculate bmi and lean-to-fat content?
Welcome to the community, @Lindamattila (or tervetuloa )!
You don’t have to calculate BMI, as it’s displayed for you in your Dashboard (if you’re accessing your account in a browser): just click on the Weight tile and on See more at the bottom, or use this direct link. You’ll also see lean vs. fat mass, provided you have a scale that can estimate your body fat %.
The same metrics are also available in the mobile app: click on the Weight tile and swipe to the left.
BMI is just a ratio between your height and your weight, so you can use Excel or your phone’s calculator to obtain it if you prefer. You can also plug in your data in an online calculator such as this one.
Dominique | Finland
Ionic, Aria, Flyer, TrendWeight | Windows 7, OS X 10.13.5 | Motorola Moto G6 (Android 9), iPad Air (iOS 12.4.4)
Take a look at the Fitbit help site for further assistance and information.
09-09-2017 19:02
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

09-09-2017 19:02
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
@Lindamattila wrote:how do I calculate bmi and lean-to-fat content?
@tiredmama wrote:I opened my account yesterday, entered weight, but do not know how to calculate my % body fat. Can someone help me with this please.
Look at the post right above yours.
Link to site for measurement method of estimating body fat %.
Actually, this whole topic has been about that question - merely reading the responses would have yielded several answered.
There is no correlation between BMI and BF%.
Help the next searcher of answers, mark a reply as Solved if it was, or a thumbs up if it was a good idea too.
05-13-2020 12:03
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

10-25-2020 13:11
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

10-25-2020 13:11
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
I recently purchased the Aria Air and since day one it has not been calculating. It is working fine. How can I resolve this?
10-26-2020 08:15
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

10-26-2020 08:15
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
@MaiMai2015 wrote:I recently purchased the Aria Air and since day one it has not been calculating. It is working fine. How can I resolve this?
So is it "working fine", or "has it not been calculating"?
Those are opposing ideas really.
It's a super simple computer, standard computer troubleshooting, pull the batteries, re-enter your info, try again.
Still failing - you won't be able to resolve it yourself - call support that is shown in documentation.
Or at least start on the part of Fitbit Forums regarding a specific product.
Help the next searcher of answers, mark a reply as Solved if it was, or a thumbs up if it was a good idea too.

10-26-2020 16:04
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post


10-26-2020 16:04
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
@MaiMai2015 -- the Aria Air does not have a body fat feature. It just displays your weight and then syncs that to your fitbit account via bluetooth (where you can see BMI, but not body fat).
Scott | Baltimore MD
Charge 6; Inspire 3; Luxe; iPhone 13 Pro

06-13-2021 06:31
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

06-13-2021 06:31
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Fitbit should calculate it for you. If you go online to find a BMI calculator, three sites will give you three different numbers. Fitbit doesn't do it automatically because they want you to buy and sync the scale. Very negative feelings about that.

06-13-2021 06:51
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

06-13-2021 06:51
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
@Chezwick wrote:Fitbit should calculate it for you. If you go online to find a BMI calculator, three sites will give you three different numbers. Fitbit doesn't do it automatically because they want you to buy and sync the scale. Very negative feelings about that.
Just so you are aware - BMI has nothing to do with bodyfat% this topic is about.
Can't tell what post your response is to so perhaps it does make more sense - but 3 sites will give exactly the same BMI figure if you use the same height and weight. Only 1 formula for BMI.
Help the next searcher of answers, mark a reply as Solved if it was, or a thumbs up if it was a good idea too.
06-13-2021 06:52
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

06-13-2021 06:52
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
There are very few BMI calculators which are even remotely accurate for many folks, the worst of course are the height and weight charts. As far as I know, the only tried and true method of body fat calculation is the full immersion into water technique to determine how much you displace, but obviously that kind of calculation is not terribly convenient on a regular basis.

06-30-2021 22:35
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

09-29-2022 05:21
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

09-29-2022 05:21
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
- Who Voted for this post?
That's BMI, the body mass index. Has nothing to do with fat.
11-27-2022 07:45
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

11-27-2022 07:45
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Body fat percentage is more accessible than BMI. BMI doesn't consider muscle vs fat.

07-30-2023 16:15
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post

07-30-2023 16:15
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Hi Dominique.
I came to this forum hoping to find out how Fitbit populates that body fat number. It asked no questions about my dimensions, no pinch measurement at the waist. It only knows my age, weight and height.
At least Fitbit knows my activity levels for several years but any number it provides could still only be a really rough guess.
If anyone from the technical end of Fitbit ever reads this, maybe they can weigh in on what that number represents?

08-01-2023 04:42
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post


08-01-2023 04:42
- Mark as New
- Bookmark
- Subscribe
- Permalink
- Report this post
Hello @Davetopaz and welcome to the Community. Fitbit populates that number two ways. If you have an Aria or Aria 2 scale (both discontinued) or a different brand of body analysis scale that can link to your Fitbit account, your body fat percent will get recorded when the data transfers to your account. There are other ways to estimate body fat (skin calipers, etc.). If you estimate your body fat on your own, you tap on the "+" sign on your weight tile and enter the value.
Laurie | Maryland
Sense 2, Luxe, Aria 2 | iOS | Mac OS
Take a look at the Fitbit help site for further assistance and information.

