We know that as a society, Americans are overweight. But determining just how heavy each of us is as individuals is a little trickier.

Right now, the most common means of measurement is the body mass index, or BMI. The BMI measures weight relative to height and is inexpensive and simple. However, critics say it’s also flawed, inaccurate and limited. The chief complaint: BMI doesn’t accurately calculate body fat. So athletes are judged as overweight and elderly people… who may have a lot of fat… don’t score as high. But more sophisticated measurements, such as body scans or air chambers, are too costly for everyday use.

A new study published in the journal Pediatrics suggests there’s another way to calculate body mass that is more accurate than BMI: measuring neck circumference.

The size of your neck can say a lot about you. A wide circumference is associated with obesity-related conditions such as sleep apnea, diabetes and hypertension.

In the study, scientists examined about one-thousand children and recorded their heights, weights and neck circumference. They found that a six-year-old boy with a neck circumference greater than eleven-point-two inches was about three-and-a-half times more likely to be overweight than his smaller peers. Using those calculations, they created neck measurements that could be used to gauge a child’s risk of being overweight or obese.

Measuring body parts to determine mass isn’t new. The stumbling block is doing it accurately. For example, it’s notoriously hard to figure out where to put the tape measure on a person’s waist. The neck is more straightforward.

So the next time you’re looking to judge body fat, you might want to put away that old, outdated calculator. Consider picking up a tape measure instead.