BMI Guide: What Is a Healthy Weight? BMI Chart & Calculator

What Is BMI?

Body Mass Index (BMI) is a screening tool that estimates body fat based on height and weight. The formula is: BMI = weight (kg) ÷ height (m)². In US customary units: BMI = (weight in lbs × 703) ÷ (height in inches)². While BMI doesn't directly measure body fat, it correlates well with body fatness for most adults and is widely used as an initial health screening tool.

BMI Categories

Underweight: BMI below 18.5
Normal / Healthy weight: BMI 18.5–24.9
Overweight: BMI 25.0–29.9
Obese, Class I: BMI 30.0–34.9
Obese, Class II: BMI 35.0–39.9
Obese, Class III (severe): BMI 40 and above

Healthy Weight Ranges by Height

Here are healthy weight ranges (BMI 18.5–24.9) for common heights:

5'0" (152 cm): 97–128 lbs (44–58 kg)
5'4" (163 cm): 108–145 lbs (49–66 kg)
5'6" (168 cm): 115–154 lbs (52–70 kg)
5'8" (173 cm): 122–164 lbs (55–74 kg)
5'10" (178 cm): 132–174 lbs (60–79 kg)
6'0" (183 cm): 140–184 lbs (63–83 kg)
6'2" (188 cm): 148–194 lbs (67–88 kg)

Limitations of BMI

BMI is a useful population-level screening tool, but it has real limitations for individuals:

Doesn't distinguish muscle from fat: A muscular athlete may have a "overweight" BMI despite very low body fat. A sedentary person may have a "healthy" BMI with high body fat percentage.
Age differences: Older adults typically have more body fat at the same BMI compared to younger adults.
Sex differences: Women naturally have more body fat than men at the same BMI.
Ethnicity: Some populations (particularly South and East Asian) face higher health risks at lower BMI values. Some organizations recommend lower BMI thresholds for these groups.

Waist Circumference: A Complementary Measure

Abdominal fat (visceral fat around internal organs) is associated with greater health risk than fat stored elsewhere. Waist circumference provides additional context beyond BMI:

Men: Less than 40 inches (102 cm) is considered healthy; above 40 inches indicates increased risk
Women: Less than 35 inches (88 cm) is considered healthy; above 35 inches indicates increased risk

Measure your waist at the level of the navel (not the belt line), after exhaling normally, standing relaxed.

What to Do If Your BMI Is Outside the Healthy Range

If your BMI is above 25 or below 18.5, consult a healthcare provider before making significant dietary or exercise changes. A doctor or registered dietitian can provide personalized guidance based on your full health picture — not just your BMI. Gradual, sustainable changes (losing 0.5–1 lb per week) are more effective long-term than rapid weight loss programs.

Frequently Asked Questions

What is a healthy BMI range?

A BMI between 18.5 and 24.9 is considered the healthy (normal) range for most adults. Values below 18.5 indicate underweight status; 25–29.9 is overweight; 30 and above is classified as obese. These thresholds are the same for men and women, though the same BMI may represent different amounts of body fat depending on age, sex, and ethnicity.

Is BMI accurate for athletes?

BMI is not accurate for highly muscular athletes. Muscle is denser than fat, so an athlete with very low body fat may have an 'overweight' or even 'obese' BMI. Body fat percentage measurement (via DEXA scan, hydrostatic weighing, or skinfold calipers) is a more accurate assessment of body composition for athletes and very active individuals.

What's a healthy weight for 5'6"?

At 5'6" (168 cm), a healthy BMI of 18.5–24.9 corresponds to a weight range of approximately 115–154 lbs (52–70 kg). The specific number that's right for you depends on your body composition, muscle mass, age, and overall health — not just height. Use this range as a guideline, not a precise target.

Can BMI be different for men and women?

The BMI formula and categories are the same for men and women. However, healthy body fat percentages differ: women typically have 20–25% body fat at a healthy BMI, while men have 10–15%. This means two people with the same BMI (say, 22) will have different actual body fat percentages based on sex. Some researchers advocate for sex-specific BMI thresholds, but current clinical guidelines use the same values for both.

What should I do if my BMI is too high?

A BMI over 25 warrants lifestyle attention, but focus on sustainable changes: increase physical activity (150 min/week of moderate activity is the standard recommendation), reduce processed food intake, and improve sleep quality. A calorie deficit of 250–500 calories per day produces gradual, sustainable weight loss of 0.5–1 lb per week. See a doctor if your BMI is 30 or above — they can rule out underlying conditions and provide personalized guidance.