BMI is determined by your weight divided by your height squared. Click here if you want to see the math of it, get help converting your numbers from the American Standard (inches/pounds) to the metric, or you can scroll to the bottom to get a couple links for some calculators that do all the math for you.
But wait! According to the article above, for 18% of the population, the BMI incorrectly determines if you are healthy or not. So why are we still using it? In school, that would get a B-… which to me says that the BMI kinda understands human health and kinda doesn’t.
Can we please use body fat percent instead? I think the reason the uptake has been slow on this change is money. In order to measure body fat percent you need extra equipment, like the seven different options mentioned here (click on one the pics to learn about each method). These range in price from $20 to several thousand dollars. However, increased price is related to increased accuracy in this case, unfortunately. And the gold standard– hydrostatic weighing– is awful! I had to do it twice in school, so I would know how to do it and how to coach someone through it, because it is panic inducing. (You have to go underwater and expel as much air out of your lungs as you can and sit there while someone calculates the measurement. And if your measure-er is slow at math, you could be sitting there feeling like you’re drowning, for a while.) However, I think if you can get your hands on a 4 lead scanner like this, it will be good enough for non-research purposes and cheap enough for common use in medical offices, gyms, etc.
And speaking of those offices and gyms, the next time you visit one of those and get weighed next to a BMI calculation poster like the one at the top of the page, can you PLEASE challenge them as to why they are using outdated methods? It’s been 10 YEARS since the study revealing that BMI doesn’t work for 18% of the population came out. It’s time to change.
P.S.– You can click on either of those charts to expand them to read them better. Don’t bother expanding the BMI chart at the top, because you don’t need to know those numbers anyway really!