What is BMI?
BMI (Body Mass Index) is a simple measure that uses your height and weight to estimate whether you're at a healthy weight. Developed by mathematician Adolphe Quetelet in the 1830s, it's now the most widely used screening tool by healthcare providers worldwide to categorize individuals as underweight, normal weight, overweight, or obese.
While BMI doesn't directly measure body fat, it correlates reasonably well with more direct measures for most people. Use the body mass index calculator above to find your BMI instantly.
BMI formula
Metric
BMI = weight (kg) ÷ height (m)²
Example: 70 kg ÷ (1.75)² = 22.9
Imperial
BMI = (lbs × 703) ÷ height (in)²
Example: (154 × 703) ÷ (69)² = 22.7
BMI categories
The World Health Organization (WHO) defines these BMI categories for adults:
| Category | BMI Range |
|---|---|
| Underweight | 0 – 18.5 |
| Normal weight | 18.5 – 25 |
| Overweight | 25 – 30 |
| Obese (Class I) | 30 – 35 |
| Obese (Class II) | 35 – 40 |
| Obese (Class III) | 40+ |
BMI chart by height and weight
This BMI chart shows weight boundaries (in lbs) for each BMI category at common heights:
| Height | Normal (lbs) | Overweight | Obese starts |
|---|---|---|---|
| 4'10" | 88–119 | 120–142 | 143+ |
| 5'0" | 94–127 | 128–152 | 153+ |
| 5'2" | 101–135 | 136–163 | 163+ |
| 5'4" | 108–146 | 147–175 | 176+ |
| 5'6" | 115–155 | 156–186 | 187+ |
| 5'8" | 122–164 | 165–197 | 198+ |
| 5'10" | 129–174 | 175–209 | 210+ |
| 6'0" | 137–184 | 185–221 | 222+ |
| 6'2" | 144–194 | 195–233 | 234+ |
| 6'4" | 152–205 | 206–246 | 246+ |
Body fat percentage chart
While BMI is useful, a body fat chart gives a more complete picture of body composition. Body fat percentage measures the actual proportion of fat tissue in your body:
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average (healthy) | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Body fat can be measured with calipers, bioelectrical impedance scales, or DEXA scans. Two people can have the same BMI but very different body fat percentages — which is why combining BMI with body fat analysis provides a more accurate health assessment.
Ideal weight by height and gender
Wondering what the normal weight for a 6'2 male is? A healthy range is 148–200 lbs (BMI 19–25.5). For a 5'2 female, a healthy weight ranges from 99–132 lbs. The table below shows healthy weight ranges by height for both men and women based on a BMI of 19–25:
| Height | Male (lbs) | Female (lbs) |
|---|---|---|
| 5'0" | 95–128 | 90–120 |
| 5'2" | 104–140 | 99–132 |
| 5'3" | 107–145 | 102–136 |
| 5'4" | 111–149 | 105–140 |
| 5'6" | 118–159 | 112–150 |
| 5'8" | 125–168 | 118–159 |
| 5'9" | 128–173 | 122–164 |
| 5'10" | 132–178 | 125–168 |
| 5'11" | 136–183 | 129–174 |
| 6'0" | 140–189 | 133–179 |
| 6'1" | 144–195 | 137–185 |
| 6'2" | 148–200 | 141–190 |
| 6'3" | 152–206 | 145–196 |
A healthy weight for a 5'2 woman is 99–132 lbs. Normal 5'3 female weight ranges from 102–136 lbs. Appropriate weight for 5'6: 118–159 lbs (male) or 112–150 lbs (female).
Average 5'9 male weight is 128–173 lbs. Healthy weight for a 5'10 male: 132–178 lbs. 5'11 male weight healthy range: 136–183 lbs.
Average weight for 6'1 male: 144–195 lbs. 6'2 ideal weight male: approximately 155–175 lbs for an athletic build, or 148–200 lbs for the full healthy BMI range. Average weight for 6'3 male: 152–206 lbs.
Ranges based on BMI 19–25. Actual ideal weight depends on frame size, muscle mass, and individual health factors.
Limitations of BMI
While BMI is a useful screening tool, it has important limitations:
- Doesn't distinguish fat from muscle. Athletes and bodybuilders may be classified as "overweight" despite low body fat.
- Doesn't account for fat distribution. Belly fat (visceral fat) carries more health risk than fat distributed elsewhere.
- Age and sex differences. Women naturally carry more fat; older adults lose muscle mass — same BMI, different health implications.
- Ethnic variations. Some populations (e.g., South Asian) face higher metabolic risk at lower BMI thresholds.
Tip: For a more complete picture, combine BMI with waist circumference measurement. A waist over 40" (men) or 35" (women) indicates elevated health risk regardless of BMI.
Ideal body weight formulas
Several ideal body weight formulas exist for estimating a healthy weight by height:
Devine Formula
Men: 50 kg + 2.3 kg per inch over 5'
Women: 45.5 kg + 2.3 kg per inch over 5'
Robinson Formula
Men: 52 kg + 1.9 kg per inch over 5'
Women: 49 kg + 1.7 kg per inch over 5'
FAQs
What is BMI?
BMI (Body Mass Index) is a numerical value calculated from your weight and height. It's used as a screening tool to categorize people into weight categories: underweight, normal weight, overweight, and obese. The formula is: BMI = weight (kg) ÷ height (m)². While it doesn't directly measure body fat, it correlates with more direct measures of body fat in most people.
How do you calculate BMI?
Using metric units: BMI = weight in kilograms ÷ (height in meters)². For example, a person weighing 70 kg and 1.75 m tall: 70 ÷ (1.75 × 1.75) = 22.9. Using imperial units: BMI = (weight in pounds × 703) ÷ (height in inches)². For example, 154 lbs and 69 inches: (154 × 703) ÷ (69 × 69) = 22.7.
What is a healthy BMI?
A healthy (normal) BMI ranges from 18.5 to 24.9. Below 18.5 is classified as underweight, 25.0 to 29.9 is overweight, and 30.0 and above is obese. A BMI of 22 is often cited as the midpoint of the healthy range. However, BMI is just one indicator of health — other factors like waist circumference, blood pressure, blood sugar, and physical fitness matter too.
Is BMI accurate for muscular people?
No — BMI has a well-known limitation for muscular or athletic individuals. Since muscle weighs more than fat per unit of volume, a very muscular person may have a high BMI (overweight or obese range) while having a low body fat percentage. For athletes, body composition measurements (like DEXA scans, calipers, or bioelectrical impedance) are more accurate indicators than BMI.
What are the BMI categories and ranges?
The WHO BMI categories for adults are: Underweight: BMI below 18.5. Normal weight: 18.5 to 24.9. Overweight: 25.0 to 29.9. Obese Class I: 30.0 to 34.9. Obese Class II: 35.0 to 39.9. Obese Class III (severe): 40.0 and above. These ranges are the same for men and women, though health risks at a given BMI may differ by sex.
What is ideal body weight?
Ideal body weight (IBW) is an estimated weight considered healthy for a given height. Common formulas include the Devine formula (Men: 50 kg + 2.3 kg per inch over 5 feet; Women: 45.5 kg + 2.3 kg per inch over 5 feet) and the Robinson formula (Men: 52 kg + 1.9 kg per inch over 5 feet; Women: 49 kg + 1.7 kg per inch over 5 feet). These are estimates — actual ideal weight varies by frame size and muscle mass.
What is the difference between BMI and body fat percentage?
BMI is a ratio of weight to height — it does not directly measure fat. Body fat percentage measures the actual proportion of fat tissue in your body. A healthy body fat percentage is roughly 10–20% for men and 18–28% for women. Two people can have the same BMI but very different body fat percentages (e.g., a muscular athlete vs. a sedentary person of the same height and weight).
Is BMI different for women vs. men?
Many people search for a BMI calculator for women or BMI calculator for men specifically — but the BMI formula and category ranges are the same for men and women. However, women naturally carry more body fat than men at the same BMI. A woman with a BMI of 24 likely has a higher body fat percentage than a man at BMI 24. Some health organizations suggest that women's health risk thresholds may differ slightly, but the standard WHO categories remain the same for both sexes.
Can BMI change with age?
BMI itself changes only if your weight or height changes. However, body composition shifts with age — older adults tend to lose muscle mass and gain fat, even at the same weight. This means a 70-year-old with a BMI of 25 likely has more body fat than a 25-year-old with the same BMI. Some researchers suggest that slightly higher BMIs (25–27) may be associated with lower mortality risk in older adults.
How do I know if I'm at a healthy weight?
Use our BMI calculator above — enter your height and weight to get your BMI category instantly. A BMI between 18.5 and 24.9 is considered healthy. For a more complete picture, consider body fat percentage and waist circumference alongside BMI. Waist measurements above 40 inches (men) or 35 inches (women) indicate elevated health risk regardless of BMI. Consult your doctor for a comprehensive assessment.
How can I lower my BMI?
To lower your BMI, you need to reduce your weight while maintaining your height (obviously). Evidence-based approaches: 1) Create a caloric deficit of 500–750 calories/day for 1–1.5 lbs/week weight loss. 2) Increase physical activity — aim for 150+ minutes of moderate exercise per week. 3) Focus on whole foods, protein, and fiber to maintain satiety. 4) Get adequate sleep (7–9 hours) — poor sleep is linked to weight gain. A BMI reduction from 30 to 25 for a 5'8" person means losing about 33 lbs.
Also known as a calculadora de IMC — calculate your Body Mass Index (Indice de Masa Corporal) in any unit system. This free tool works for both imperial and metric measurements.