Help with body fat percentage calculations

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dengarrett
dengarrett Posts: 367
in Fitness and Exercise
Ok - this is a stupid question but it has continued to elude me. I read this example froma post:

Jim weighs 170 lbs with 20% body fat. Mark weighs 175 lbs (5 lbs more) at 10% body fat. This means Jim has 11 lbs of fat on him, while Mark — even at the higher weight — carries only 5.5 lbs of fat.

And I read this from Wikipedia:

A person's body fat percentage is the total weight of the person's fat divided by the person's weight.

I can't make these numbers add up. 11 / 170 = 0.064705882. How do you get to the 20% number? Assuming the example from the post is accurate of course.

Replies

  • georgeguns1
    georgeguns1 Posts: 3
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    jim would have 34 pounds of fat at 20% bf, mark 17.5 pounds at 10%
  • taiyola
    taiyola Posts: 964 Member
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    :noway: saaaay whattt

    Isn't this an individual thing? Like, some skinny people aren't toned? I have no idea!

    BBBBBBBUMP!
  • EmmaShorter
    EmmaShorter Posts: 298
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    How do you work out your percentage of body fat?
  • WolffEarl
    WolffEarl Posts: 379 Member
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    Haha, I know exactly what you mean. I think I saw this exact same post somewhere also recently and realized right away that the math is way off. 20% for a 170 person is 34 lbs of fat, whereas 10% for a 175 lb person is 17.5 pounds of fat, so a difference of 16.5 lbs of fat between the two of them. The relative proportion of these two individuals, one having almost twice the amount of total fat is reasonably close, the actual numbers are way off.
  • jenbk2
    jenbk2 Posts: 623 Member
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    Those calculators are not correct. The only accurate BMI is when they do it with those pinchers. I actually had 6% more fat when they did the test.
  • dengarrett
    dengarrett Posts: 367
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    Haha, I know exactly what you mean. I think I saw this exact same post somewhere also recently and realized right away that the math is way off. 20% for a 170 person is 34 lbs of fat, whereas 10% for a 175 lb person is 17.5 pounds of fat, so a difference of 16.5 lbs of fat between the two of them. The relative proportion of these two individuals, one having almost twice the amount of total fat is reasonably close, the actual numbers are way off.
    Thanks - that is what made sense to me but wanted to be sure I understood it correctly.
  • farmgirl88
    farmgirl88 Posts: 91 Member
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    How do you work out your percentage of body fat?

    If you don't have access to a scale that measures your body fat--you can use this simple calculator that will get you a rough estimate :)

    livestrong.com/tools/body-fat-calculator/

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