If you're looking to know your exact body fat percentage, no one device is 100% accurate. Still, if it's important to you to have a figure to go on, it might be worth the cost to invest in a high-tech procedure somewhere to get a closer reading. A machine will rule out human error.
But if you want to know your percentage to track your progress, make sure to use the same procedure over and over. This can get pricey if you choose the high-tech route. I use a Tanita Bodyfat Scale. It's probably way off but at least it's consistent (and free!) It will tell me how much I differ from last month or last year, which is what I truly want to know.
It's like when you weigh yourself at a friend's house and the scale says something different than yours. Which one is accurate? Who cares: if you have goals, all you need is an accurate measurement of your change
. Three pounds or two percentages up or down are meaningless numbers if you are feeling and looking better, anyway.
I'm not a big proponent of using body fat percentage as a measure of health anymore because I've seen low BFP's who are weak as chicken bones on so many levels and high BFP's with perfect blood pressure and cholesterol who can out-hike me up a mountain. Plus, they are better huggers!
Happy and capable is my goal.