What is a healthy BMI?

A healthy BMI for adults is 18.5–24.9, per the WHO and CDC. Within this range, risks of issues like diabetes, heart disease, and some cancers are lowest. Still, BMI isn’t the whole story — two people can share the same BMI yet differ in fitness and body fat. Use it as a screening tool, alongside body fat %, waist size, and regular check-ups.

You’re considered overweight when your BMI is 25.0–29.9, and obese at 30 or higher. These ranges link to higher risks of diabetes, hypertension, and heart disease. Still, BMI isn’t perfect — muscular people may score “overweight” yet be healthy. Use it as one signal among lifestyle, family history, and other health factors.

To calculate BMI, use your weight and height: Metric: BMI = weight (kg) ÷ [height (m)²] Imperial: BMI = (703 × weight (lbs)) ÷ [height (in)²] Example: 70 kg and 1.75 m → 22.9. Or 154 lbs and 69 in → 22.7. Both give nearly the same result. Or skip the math and try our BMI Calculator for a quick answer.

The number 703 is just a conversion factor. The metric formula uses kg and meters, but pounds and inches don’t align the same way. When BMI was adapted for the U.S., multiplying by 703 made results match the metric version. Without it, BMI would read too low — 703 simply keeps both systems consistent and accurate.

Not always. BMI can’t tell muscle from fat, so athletes with lots of lean mass may score “overweight” or “obese” despite low body fat. A bodybuilder’s BMI might hit 30+, yet they’re perfectly healthy. For muscular people, body fat % or waist-to-hip ratio are better indicators. If you’re fit, a “high” BMI likely reflects muscle, not fat.

For kids and teens, BMI is calculated the same way as for adults but interpreted differently. The CDC uses age- and sex-specific growth charts to find a child’s BMI percentile—showing how they compare to peers. For instance, the 90th percentile means higher than 90% of kids that age. Doctors use these percentiles, not adult BMI cutoffs.

The safest way to lower BMI is through healthy eating, regular activity, and consistency. Focus on lean protein, fruits, veggies, whole grains, and healthy fats; limit sugary drinks and processed snacks. Get 150+ minutes of exercise weekly—walk, swim, cycle, or lift. Skip crash diets; aim for gradual loss (0.5–1 kg / 1–2 lbs per week). Track progress with our TDEE Calculator.