BMI Calculator

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BMI Calculator

Calculate your Body Mass Index and health status

cm
kg
years
Quick Tips
  • BMI is a screening tool, not a diagnosis — it cannot distinguish muscle from fat.
  • Athletes and very muscular people often register as "overweight" or "obese" despite low body fat.
  • Waist circumference and body fat percentage are often better individual health indicators than BMI alone.
  • Track your BMI over time rather than reacting to a single measurement.

Your BMI

22.9
Normal Weight
Ideal Weight Range
-
Weight Status
-
BMI is a screening tool and not a diagnostic tool. It does not directly measure body fat or account for muscle mass. Consult a healthcare professional for personalized advice.

Last updated: August 10, 2026

BMI: What the Numbers Actually Mean

BMI = weight (kg) ÷ height (m)². Or in pounds: weight × 703 ÷ height² (inches). A 5'9" person at 170 lbs = BMI 25.1 (overweight). Same person at 169 lbs = 24.9 (normal). One pound difference changes your classification.

BMI was invented in 1832 for population statistics, not individual health. It can't distinguish muscle from fat—bodybuilders register as "obese," elderly with muscle loss as "healthy." Better indicators: waist circumference, body fat %, blood pressure, cholesterol. But BMI remains standard because it's simple and free.

BMI Categories

BMI Range Category Health Risk
< 18.5 Underweight Malnutrition, weak immune system, osteoporosis
18.5 - 24.9 Normal Lowest mortality risk
25.0 - 29.9 Overweight Increased risk heart disease, diabetes
30.0 - 34.9 Obese Class I High risk chronic disease
35.0 - 39.9 Obese Class II Very high risk
≥ 40.0 Obese Class III Extremely high risk, life-threatening

BMI Limitations

Doesn't Account For

  • Muscle mass: Athletes labeled "overweight"
  • Age: Older adults lose muscle, appear healthier
  • Sex: Women naturally have more body fat
  • Ethnicity: Asians have higher risk at lower BMI
  • Fat distribution: Belly fat worse than leg fat

Better Health Indicators

  • Waist circumference: >40" men, >35" women = risk
  • Waist-to-hip ratio: Central obesity marker
  • Body fat %: 25%+ men, 32%+ women = high
  • Blood tests: Glucose, cholesterol, inflammation
  • Blood pressure: <120/80 optimal

Quick Weight Goals

5'4" (163 cm)

  • Normal weight: 108-145 lbs
  • Overweight starts: 146 lbs
  • Obese starts: 175 lbs

5'9" (175 cm)

  • Normal weight: 125-169 lbs
  • Overweight starts: 170 lbs
  • Obese starts: 203 lbs

6'0" (183 cm)

  • Normal weight: 140-183 lbs
  • Overweight starts: 184 lbs
  • Obese starts: 221 lbs

6'2" (188 cm)

  • Normal weight: 148-194 lbs
  • Overweight starts: 195 lbs
  • Obese starts: 234 lbs

Action Steps by Category

Underweight (BMI < 18.5)

See doctor to rule out medical causes. Increase calories with nutrient-dense foods. Strength training to build muscle.

Normal Weight (BMI 18.5-24.9)

Maintain with balanced diet and 150+ minutes weekly moderate exercise. Monitor waist size annually.

Overweight (BMI 25-29.9)

Lose 5-10% body weight to reduce health risks. Cut 500 calories/day = 1 lb/week loss. Check blood pressure and cholesterol.

Obese (BMI ≥ 30)

Consult doctor before starting diet. Screen for diabetes, sleep apnea. Consider medical weight loss programs. Even 5% weight loss improves health markers significantly.

How we calculate this

Method
Body Mass Index
Formula
BMI = weight kg ÷ (height m)²
Source
World Health Organization BMI classification: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30 and above obese.
Limitations
BMI does not distinguish muscle from fat and was never designed to assess an individual. It misclassifies muscular and older bodies in opposite directions.
Last reviewed

Found a discrepancy? Tell us and we will check it — corrections are published on this page. Report an issue

Frequently Asked Questions

For populations, yes — it's a well-validated screening tool used by health organizations worldwide. For any single individual, it can be misleading since it doesn't measure body fat directly, only weight relative to height.

A BMI between 18.5 and 24.9 is considered normal weight by WHO standards. Research suggests the lowest mortality risk typically falls around BMI 22-23 within that range.

BMI only measures weight relative to height — it can't distinguish muscle from fat. Athletes and bodybuilders with very low body fat can be classified as "overweight" or even "obese" by BMI alone.

The standard adult BMI categories apply the same way to adults aged roughly 20-65. Children and teens are assessed differently, using age- and sex-specific percentile growth charts rather than fixed BMI thresholds.

Waist circumference is often considered a better predictor of health risk since it reflects abdominal fat specifically. Body fat percentage is also more accurate than BMI for assessing fitness and body composition.

Yes — a BMI under 18.5 is classified as underweight, which carries its own health risks including a weakened immune system, osteoporosis, and fertility issues.

A safe, sustainable rate is generally 1-2 pounds per week. Even a modest 5-10% total weight loss has been shown to meaningfully improve health markers like blood pressure and blood sugar.

Yes — some populations face elevated health risks at lower BMI values. The WHO recommends a lower BMI range (roughly 23-27.5) for Asian adults, compared to 25-30 used for the general population.

Tracking waist circumference and how your clothes fit alongside BMI often gives a fuller picture, since weight and BMI can fluctuate daily with water retention and other factors. Weighing yourself weekly at the same time of day gives more consistent data than daily readings.

Consider a checkup if your BMI is over 30 (to screen for related conditions like diabetes or sleep apnea), under 18.5 (to rule out underlying medical causes), or if you experience rapid weight change of 10 or more pounds in a month.

No — this calculator uses adult BMI thresholds. Children and teens should be assessed using pediatric growth charts that account for age and sex, since healthy BMI ranges change as kids grow.

Yes — toggle between Metric (kg, cm) and Imperial (lb, ft/in) at the top of the calculator, and your entries convert automatically.

Yes — use "Copy Link" to get a URL that encodes your height and weight, or export your result as PDF, CSV, or JSON using the buttons below your results.

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Your BMI
22.9
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