BMI is calculated the same way for men and women: divide your weight by your height squared. If you’re using pounds and inches, you multiply the result by 703. The whole calculation takes about 30 seconds with a phone calculator, and the number you get falls into standard categories that estimate whether your weight poses health risks.
The BMI Formula
If you’re working in pounds and inches, here’s the formula:
BMI = (weight in pounds ÷ height in inches ÷ height in inches) × 703
Say you’re 5’10” (70 inches) and weigh 185 pounds. You’d divide 185 by 70, which gives you 2.643. Divide that by 70 again: 0.03776. Multiply by 703, and your BMI is 26.5.
If you’re using metric units, it’s simpler:
BMI = weight in kilograms ÷ (height in meters × height in meters)
So a man who weighs 84 kg and stands 1.78 m tall would calculate 84 ÷ (1.78 × 1.78) = 84 ÷ 3.168 = 26.5.
What Your Number Means
The standard categories used by most health organizations are:
- Below 18.5: Underweight
- 18.5 to 24.9: Healthy weight
- 25.0 to 29.9: Overweight
- 30.0 and above: Obese
These ranges were developed using data primarily from non-Hispanic white populations, and they apply identically to men and women. That’s worth noting because men and women carry fat very differently. Men tend to store more fat around the midsection, while women store more in the hips and thighs. BMI doesn’t distinguish between these patterns, even though belly fat is more strongly linked to heart disease and metabolic problems.
Why BMI Can Be Misleading for Men
BMI measures total weight relative to height. It cannot tell you how much of that weight is muscle and how much is fat, or where the fat sits on your body. For men who lift weights, play sports, or carry above-average muscle mass, this is a real problem. A muscular man can easily land in the “overweight” or even “obese” range while having relatively low body fat. Football players and bodybuilders routinely show BMIs above 30 despite being lean.
This also plays out along racial lines. Research from the Obesity Medicine Association notes that BMI tends to overestimate overweight status in Black men because their higher average muscle mass pushes the number up without reflecting increased body fat.
The American Medical Association adopted a policy recognizing these limitations, recommending that BMI be used alongside other measures rather than as a standalone number. The AMA specifically flagged that BMI loses its predictive value when applied to individuals, even though it correlates well with body fat across large populations. In other words, it’s a decent screening tool for trends but a blunt instrument for any one person.
Lower Thresholds for Asian Men
If you’re of Asian descent, the standard BMI categories may underestimate your risk. The WHO recommends lower cut-offs for Asian populations: overweight starts at 23 (instead of 25) and obesity at 25 (instead of 30). Some guidelines use an obesity threshold of 27.5. The reason is that Asian men tend to develop metabolic complications like type 2 diabetes and cardiovascular disease at lower BMIs than white men, partly because they carry proportionally more visceral fat at the same BMI.
Waist Circumference: A Better Companion Measure
If you want a clearer picture of whether your weight is actually affecting your health, pair your BMI with a waist measurement. Wrap a tape measure around your midsection at the level of your navel, standing relaxed. For men, a waist circumference of 40 inches or more signals elevated risk for heart disease, type 2 diabetes, and high blood pressure. A waist-to-hip ratio of 1.0 or higher carries similar implications.
Waist circumference works better than BMI at capturing visceral fat, the deep abdominal fat that wraps around your organs and drives metabolic problems. Two men with the same BMI of 27 can have very different health profiles depending on whether that weight sits in their shoulders and legs or packs around their midsection. The tape measure catches what the formula misses.
How to Use Your BMI Practically
Think of BMI as a starting point, not a verdict. If your number falls in the healthy range and your waist is under 40 inches, you’re in good shape by these metrics. If your BMI is in the overweight range but you exercise regularly and carry visible muscle, the number is likely overstating your risk. If your BMI is above 30 and your waist is over 40 inches, both measures are pointing in the same direction and it’s worth paying attention.
Tracking your BMI over time can also be useful. A steady climb of two or three points over a few years reflects real weight gain, regardless of where you started. The trend matters more than any single snapshot, and combining it with waist measurements gives you a practical, no-cost way to monitor changes that affect your long-term health.