How to Measure Your Wrist to Get Your Body Frame Size — and What It Can Tell You About Your Ideal Weight

All you have to do is look to the world of sports to see that there's no one "right" body size. From jockeys to basketball players to sumo wrestlers, bodies come in all different (and equally beautiful) shapes and sizes.

While it's never a good idea to compare your body to someone else's — we're all so unique, after all — knowing your general body frame size may help you set realistic expectations when it comes to your weight and fitness goals.

Here's how to determine your body frame size, and how that correlates to your ideal body weight and BMI.

Strange as it may sound, your body frame size can be calculated by measuring your wrist with a tape measure and comparing it to your height, according to the U.S. National Library of Medicine.

Place the tape around your wrist in the same area you wear a watch to determine the circumference of your wrist in inches.

Once you know your wrist size, compare it to your height to determine if you're small-, medium- or large-boned.

Although using a tape measure is probably the most accurate way to determine body frame size, you can also use your thumb and index finger. Wrap your thumb and forefinger around your wrist in the area you normally wear a watch.

• If your fingers overlap, you're considered small-framed.
• If your fingers touch tip to tip, you're medium-framed.
• If there's a gap between your thumb and index finger, you have a large frame.

Now that you know your body frame size, you can use it to determine your ideal body weight (IBW). While there are several formulas you can use, according to a May 2016 article in ‌The American Journal of Clinical Nutrition‌, the HAMWI method is a simple calculation you can use to estimate your weight and adjust based on your body frame size. The equations below calculate the IBW for medium-framed people; then you add or subtract 10 percent for small or large frames.

‌For women, start at 100 pounds and add 5 pounds for every inch above 5 feet:‌

IBW (lb) = 100 + 5 x (Ht – 60 in)

‌For men, start with 106 pounds and add 6 pounds for every inch above 5 feet:‌

IBW (lb) = 106 + 6 x (Ht – 60 in)

So, for example, the IBW for a 6-foot tall, medium-framed man is:

106 + 6 x (72 - 60) = 178 pounds

The IBW for a small-framed man is 10 percent less than 178, or 160 pounds, and the IBW for a large-framed man is 10 percent greater than 178, or 196 pounds.

So, for healthy men who are 6 feet tall, the IBW range is 160 to 196 pounds, depending on body frame size.

While your IBW may give you a specific number you can shoot for when you step on the scale, it may not be the best way to determine good health when it comes to your weight. Body mass index (BMI) estimates body composition and is thought to be better at determining health risks than IBW, according to another May 2016 article published in ‌The American Journal of Clinical Nutrition‌.

Like ideal body weight, a mathematical formula is used to estimate BMI; all you need is your height and weight, per the Centers for Disease Control and Prevention. Divide your weight in pounds by your height in inches squared and multiply by 703:

‌BMI = [weight / (height x height)] x 703‌

If you're 6 -foot-tall man who weighs 196 pounds, your BMI is 26.5, which places you in the overweight category on the BMI chart, even though 196 is considered an ideal weight for a large-framed man of this height.

Formulas that calculate IBW and BMI can help you get a good idea of where the scale should be ‌around‌, but they're definitely not perfect. And while BMI offers a fair estimate of body fat for most people (while IBW does not — it's a linear formula), it has its limitations, according to the Mayo Clinic. BMI underestimates body fat for older people or people with low muscle mass and overestimates body fat for those who are very muscular.

"A BMI chart is not the best for those who are building muscle and lifting weight," says Jim White, RDN, CPT, certified personal trainer and owner of Jim White Fitness & Nutrition Studios in Virginia. He notes that he's seen bodybuilders with 6 percent body fat who are considered to have obesity based on their BMI. "That's because it takes into account our average height and weight, but doesn't dissect the kind of weight we have."

The best way to figure out someone's "ideal weight," he says, is to focus on measurements like waist-to-hip ratio or body fat percentage.

"These two can be great ways to assess increased risk for diseases while being more realistic than weighing in. Weight is influenced by so many things, such as muscle mass, water, salt, food, etc," he says.

Lastly, if you need a little guidance, then talk to a certified trainer or registered dietitian, and get help setting a realistic goal weight for your body type.