BMI Calculator 2026
Calculate your Body Mass Index (BMI) instantly in metric or imperial units. Free, accurate, and worldwide — for men, women, kids, and adults.
Enter your height and weight to instantly calculate your Body Mass Index (BMI) and find out if you're underweight, healthy, overweight, or obese. Supports metric (kg, cm) and imperial (lbs, ft, in) units used worldwide.
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 16 | Severe Thinness | Very high risk |
| 16 – 16.9 | Moderate Thinness | High risk |
| 17 – 18.4 | Mild Thinness | Moderate risk |
| 18.5 – 24.9 | Healthy / Normal | Low risk |
| 25 – 29.9 | Overweight | Increased risk |
| 30 – 34.9 | Obese Class I | High risk |
| 35 – 39.9 | Obese Class II | Very high risk |
| 40 and above | Obese Class III | Extremely high risk |
* BMI is a screening tool and not a diagnostic measure. It does not account for muscle mass, bone density, age, sex, or ethnicity. Athletes, pregnant women, and elderly individuals may need additional assessments. Always consult a qualified healthcare professional for personalized medical advice.
What Is a BMI Calculator?
A BMI calculator (Body Mass Index calculator) is a free online health tool that estimates whether your weight is healthy for your height. It's the most widely used screening method by doctors, hospitals, and health organizations worldwide — including the World Health Organization (WHO), CDC, and NHS.
Our free BMI calculator works for men, women, teens, and adults worldwide. It supports both metric units (kg and cm) commonly used in Europe, Asia, Australia, and most of the world, and imperial units (pounds, feet, inches) used in the United States. Whether you're tracking weight loss, building muscle, or simply checking your health, this BMI calculator gives you instant, accurate results in seconds.
How to Use This BMI Calculator
Calculating your BMI takes less than 30 seconds:
- Choose your unit system — metric (kg, cm) or imperial (lbs, ft, in).
- Enter your gender and age — used to provide more personalized insights.
- Enter your height — in centimeters or feet/inches.
- Enter your weight — in kilograms or pounds.
- Click Calculate BMI — see your BMI score, health category, healthy weight range, and personalized insights instantly.
BMI Formula (Metric & Imperial)
The Body Mass Index formula is internationally standardized. Our calculator uses the exact same formula recommended by the WHO:
BMI = weight (kg) ÷ [height (m)]²
Imperial formula:
BMI = [weight (lbs) ÷ height (inches)²] × 703
Example: A person who is 170 cm (1.70 m) tall and weighs 70 kg
BMI = 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2 (Healthy)
BMI Chart for Adults (WHO Standard)
The World Health Organization defines BMI categories for adults aged 20 and over as follows:
| BMI Range | Category | What It Means |
|---|---|---|
| Below 18.5 | Underweight | May indicate malnutrition or health issues |
| 18.5 – 24.9 | Healthy weight | Lowest health risk range |
| 25 – 29.9 | Overweight | Increased risk of heart disease, diabetes |
| 30 – 34.9 | Obese (Class I) | High risk of chronic diseases |
| 35 – 39.9 | Obese (Class II) | Very high health risk |
| 40 and above | Obese (Class III) | Severe health risk, medical care advised |
BMI Calculator for Women vs. Men
The BMI formula is identical for men and women — the same equation is used regardless of gender. However, the interpretation can vary slightly:
BMI for women: Women naturally carry more body fat than men, even at the same BMI. Healthy women often fall in the lower half of the healthy BMI range (18.5–22). After menopause, BMI may rise due to natural hormonal changes.
BMI for men: Men typically have more muscle mass, which can push BMI higher even when body fat is low. Athletic men and bodybuilders may show "overweight" BMI while being very healthy. Always pair BMI with a body fat percentage measurement for full context.
BMI for Asians — Why the Numbers Are Different
The World Health Organization recommends lower BMI thresholds for Asian populations because Asians tend to develop health risks (especially type 2 diabetes and heart disease) at lower BMI levels:
- Underweight: Below 18.5
- Healthy: 18.5 – 22.9
- Overweight: 23 – 27.4
- Obese: 27.5 and above
If you're of South Asian, East Asian, or Southeast Asian descent, consider these adjusted thresholds when interpreting your BMI.
BMI for Kids and Teens
For children and teenagers (ages 2–19), BMI is calculated the same way but is interpreted using age-and-sex-specific percentiles based on CDC growth charts. A pediatrician will compare your child's BMI percentile to other kids of the same age and gender. For example, a BMI in the 85th–95th percentile is considered overweight for that age group. Always consult a pediatrician for accurate assessment of children's BMI.
Limitations of BMI — What It Doesn't Measure
BMI is useful, but it's not perfect. It has several important limitations:
- It doesn't measure body fat directly. A muscular athlete may have a BMI of 28 (overweight) while having only 10% body fat.
- It doesn't distinguish muscle from fat. Two people with identical BMI can have very different body compositions.
- It doesn't account for age. Older adults naturally lose muscle and gain fat, even at a stable BMI.
- It doesn't account for ethnicity. Health risk thresholds differ for Asian, African, and European populations.
- It's not suitable for pregnant women or those who are breastfeeding.
For a complete health picture, pair BMI with waist circumference, body fat percentage, and a doctor's clinical assessment.
How to Lower Your BMI — Healthy Tips
- Create a moderate calorie deficit. Aim to lose 0.5–1 kg (1–2 lbs) per week — about 500 fewer calories per day than you burn.
- Eat more protein and fiber. Both keep you full longer and reduce overeating.
- Strength train 2–3 times per week. Building muscle increases your resting metabolism so you burn more calories even at rest.
- Walk daily. Aim for 7,000–10,000 steps. Walking is the simplest, most sustainable form of exercise.
- Get 7–9 hours of sleep. Poor sleep raises cortisol and the hunger hormone ghrelin, leading to weight gain.
- Drink water, not sugary beverages. Cutting soda, fruit juice, and energy drinks alone can drop several pounds in a month.