BMI for Men: Does the Math Work?

Using body mass index (BMI) to measure health for men and people assigned male at birth (AMAB) is as accepted as it is controversial. Physiologist Chris Dempers, ACSM EP-C, and fitness specialist Colt Mcdonough explain why BMI calculators can be so divisive, but when you still might want to use them.

The 411 on BMI for men

BMI uses math to measure your body fat: It’s your weight in kilograms divided by your height in meters squared.

“BMI gives you an overall health assessment. Your number indicates if you’re in the healthy, underweight, overweight or obesity range,” says Dempers. “But it doesn’t factor in body fat or muscle mass, so there are BMI limitations.”

BMI is a one-size-fits-all tool, so it doesn’t account for naturally occurring body differences. “It’s the same BMI chart for men and women,” he notes, even though women and people assigned female at birth (AFAB) typically have more body fat.

But in a time-crunched society, the benefits of BMI measurements are clear. “Many physicians use it because it’s a quick, affordable assessment for the general population: average-sized people who don’t exercise regularly,” he adds.

BMI gives a fairly accurate measurement of where people fall in the weight range and whether the extra weight has them on the verge of Type 2 diabetes, heart disease or other conditions. “It can motivate people to jump-start a healthier lifestyle,” Dempers explains.

BMI calculator for men

To calculate your BMI, use this adult BMI calculator.

You can also use these formulas to calculate your BMI:

• U.S. units. (Weight in pounds ÷ height2 in inches) x 703 = BMI (For example: 150 pounds ÷ 65 inches2 x 703 = 26.6).
• Metric units. Weight in kilograms ÷ height2 in meters = BMI (For example: 70 kilograms ÷ 1.7 meters2 = 24.2).

BMI chart ranges for men

Health experts say a number between 18.5 to 24.9 is a healthy BMI for men and people AMAB. The same goes for women and people AFAB. Check your weight classification in the BMI chart below.

What are the limitations of BMI?

BMI is an old tool — it was developed almost two centuries ago. “At that time, they got most of their data from corpses, so that’s what healthy BMI ranges are based on,” says Dempers. “People’s average height and weight have also increased over the years, which further throws things off.”

Dempers and Mcdonough say you should take your BMI with a grain of salt if you are:

• Athletic: “For athletes, body mass index is useless, especially for males,” says Mcdonough. “Higher density muscle weighs more than fat, so their BMI range will show overweight or obesity.”
• Older: “Muscle mass is one of the first things that slowly starts declining as people age. As testosterone levels drastically drop off over time, men’s overall body fat increases — and usually in the belly area,” says Dempers. You could have the same BMI as a younger male but more body fat.
• Muscular: Some people tend to have more muscle mass, such as former athletes. “Former athletes may hold on to a decent amount of muscle mass as they age, but they’re not exercising like they were when they were playing sports,” explains Dempers. “Their BMI may still be within the healthy range for men, but they have extra belly fat that could increase their risk for chronic conditions.”

Five ways to measure your body fat (that aren’t BMI)

Dempers and Mcdonough say it’s best to view BMI as part of the puzzle. These other tools can help complete the picture:

• Dual-energy X-ray absorptiometry (DEXA). DEXA is an imaging test that measures bone density. “You can use it to tell what percentage of your body is bone mass, muscle mass and body fat,” explains Mcdonough.
• Electronic body fat scanner. Electronic body fat scanners send a small current through your body to determine your body fat percentage. Scanners are typically built into many scales. “While they typically have a standard deviation of about plus or minus seven on the accuracy scale, they still give you a good ballpark measurement,” notes Dempers.
• Mirror. Dempers says mirrors are a great tool to measure your physical progress. “It’s not about nitpicking yourself. Instead, look in the mirror at where you are and notice changes — like less belly fat — as you achieve your health goals.”
• Skinfold calipers. While it varies by age, the average body fat range for men and people AMAB is 18% to 25%. Experts consider 25% body fat and above to be the obesity range for men and people AMAB. Skinfold calipers, which look like tongs, are a tool used to measure body fat percentage. “Some athletic trainers know how to do a six-site test on your body using calipers. The results show your body fat percentage,” adds Mcdonough. “While your BMI might be in the obesity range, the skinfold caliper test can show that you’re holding more muscle density than what your BMI indicates.”
• Waist-to-hip ratio (WHR). Your WHR is your waist measurement divided by hip measurement in centimeters. Where your WHR falls within a certain range shows if you’re overweight and at risk for obesity-related conditions.

Make sure you stand up straight. To find your waist circumference, place a tape measure around the smallest part of your waist, which is typically above your belly button. Then to figure out your hip circumference, do the same with the largest part of your hips, typically the widest part of your buttocks. Divide your waist circumference by your hip circumference.

“You can have a good BMI, but your WHR could be off. You could have a big old beer belly, but on paper, your height and weight are still within the normal range,” notes Dempers. “To accurately figure out your body fat percentage, enlist an exercise physiologist or trainer at a fitness center with experience to help you.”

Then, use that information to help make positive changes. “The mantra ‘use it or lose it’ is truthful,” says Mcdonough. “If you need to lose weight or maintain muscle, stay consistent with a balanced diet and regular exercise. That can do the trick to keep you healthy for the long term.”