Body fat percentage calculators - Accuracy?

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GazelleLady
GazelleLady Posts: 131 Member
in Fitness and Exercise
Hey guys! I was just wondering if anyone has used an online body fat percentage calculator. I used the Navy Body Fat Calculator because I heard it was pretty accurate. My question is this: Is it possible for this calculator to account for the amount of muscle in my legs? It asks for the circumference of my waist, hips, and neck. However, I ride my bicycle strenuously for at least 7 hours per week (in addition to about 15 miles of running per week), so I have a lot of muscle definition in my legs. But the calculator cannot tell how much of my weight comes from muscle if it does not account for the muscle in my legs, right? Does this mean I should not take the measurement too seriously if it is higher than I think it should be? I'm just curious. Feel free to disagree.

Replies

  • GazelleLady
    GazelleLady Posts: 131 Member
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    @Fidgetbrain Hydrostatic weighing and calipers are definitely more accurate methods. I am just too cheap to try them, lol. I guess that I was just surprised to see that these online calculators had a margin of error of only 1-3%, since there are so many factors.
  • AnnPT77
    AnnPT77 Posts: 32,195 Member
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    There are a bunch of threads here about estimating body fat, and even options to post a photo (full body: side, front, back, minimal clothing like bathing suit, not undies) in the Bodybuilding topic area and get estimates from MFP-ers who are trainers (or just have opinions 😆).

    One recent thread is here:

    https://community.myfitnesspal.com/en/discussion/10833599/body-fat-calculator-us-navy-method

    It has various other methods/calculators linked & compared, not necessarily definitive/exhaustive.

    How long have you been doing the cycling/running? Clearly, volume of those will add muscle, but not as much as weight training, and not typically super fast, so the Navy calculator may not be that distorted because of that.

    Are you female? Our body fat percentages are often higher than we might have guessed, IME. 😉 (I'm female, too . . . experienced at it, at age 65. 😆)

    There are also web sites with photos of people at various BF% and weights/heights that you can use as a reality test. Can't remember if any are linked in the thread I linked above, but they're not hard to find. Accurate? Hmmm. 😉 Another input, at least.
  • GazelleLady
    GazelleLady Posts: 131 Member
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    @AnnPT77 Thanks for the reply! I have been cycling for 5 years and running for 9 years. I am a woman and I can maintain a high "watts per kilogram" for a pretty long time. This usually corresponds to a lower percent body fat, but not always. It is possible I carry some fat in my upper body but I can overcome it.

    Thank you for the link!
  • penguinmama87
    penguinmama87 Posts: 1,158 Member
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    I had a weird experience yesterday when I took my measurements and logged them into the average calculator I mention in the thread Ann referenced - even though both my weight AND several measurements decreased, whatever algorithms are used by the calculators gave me a BF percentage that was much higher than any I had previously recorded. So, at least for this particular set of measurements, I have my doubts. In my case I'm still losing weight, so I'm going to be looking for an overall downward trend over time, and weird spikes or dips can be mostly disregarded.

    What measuring body fat looks like for maintenance or recomp is probably somewhat different, though.
  • naomi9271
    naomi9271 Posts: 127 Member
    edited June 2021
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    Similar to you. I cycle around 7h/week also, but don’t run. I have been biking for 20 years. I am supposedly 26% body fat including thigh, wrist, forearm and calves measurements: here’s one that includes most of those:
    HTTPS://www.tlsslim.com/resources/measurements

    and depending on the site, up to 32% body fat if it’s just waist and hips or 30% if it includes the neck. I have a large posterior, in case you couldn’t tell, LOL.

    So I think reality is somewhere in the middle of this, and as Ann said, I chuckle test using the pictures people post with body fat described….but they vary a lot, so don’t look at just one site and think it’s accurate.

    Looking at the pictures, I don’t think I’m either 26 or 32%. Probably closer to 28 or 29, since I have some belly fat.

    But the bottom line is to not take those calculators too seriously.
  • naomi9271
    naomi9271 Posts: 127 Member
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    @Fidgetbrain Yeah, I feel ya. Hey, at least you didn’t get called obese :). We aren’t one size fits all when it comes to these calculator thingys. Guessing you’re tall and slim and with an endurance build? I’m more of a sturdy frame and built to sprint, even though I do endurance sports.
  • heybales
    heybales Posts: 18,842 Member
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    Includes another calc which includes legs.

    Accurate on any of them depends on how well your body happens to conform to the average bodies of those in the testing that were used.

    With good legs like that - probably not much.

    But at least you can track direction, which is ultimately what probably really matters.

    http://www.gymgoal.com/dtool_fat.html

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