A BMI calculator is a free online health tool that instantly computes your Body Mass Index using your height and weight — in either metric (kilograms and centimetres) or imperial (pounds and feet/inches) units — and tells you which weight category your result falls into. Enter two numbers, click calculate, and get your BMI score along with a clear explanation of what it means for your health in seconds.
Body Mass Index is one of the most widely used screening tools in medicine and public health. Doctors, nurses, dietitians, fitness professionals, insurance providers, and public health researchers use BMI every day as a quick, standardised way to assess whether a person's weight is in a healthy range relative to their height.
BMI = Weight (kg) ÷ Height (m)²
Example: Weight 75kg, Height 1.75m → BMI = 75 ÷ (1.75 × 1.75) = 75 ÷ 3.0625 = 24.49
BMI = (Weight (lbs) × 703) ÷ Height (inches)²
Example: Weight 165lbs, Height 5ft 9in (69 inches) → BMI = (165 × 703) ÷ (69 × 69) = 115,995 ÷ 4,761 = 24.36
| BMI Range | Weight Category | Health Risk Level |
|---|---|---|
| Below 18.5 | Underweight | Increased risk |
| 18.5 – 24.9 | Normal weight | Lowest risk |
| 25.0 – 29.9 | Overweight | Moderate risk |
| 30.0 – 34.9 | Obesity Class I | High risk |
| 35.0 – 39.9 | Obesity Class II | Very high risk |
| 40.0 and above | Obesity Class III | Extremely high risk |
Standard WHO BMI categories were developed primarily from data on populations of European descent. Research has consistently shown that the relationship between BMI and health risk differs significantly across ethnic groups:
People of Asian descent tend to have higher body fat percentages at lower BMI values compared to people of European descent. Many health authorities recommend lower BMI cut-off points for Asian populations:
| BMI Range | Category (Asian-Specific) |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 22.9 | Normal weight |
| 23.0 – 27.4 | Overweight |
| 27.5 and above | Obese |
BMI Does Not Distinguish Muscle from Fat. A highly muscular person — an elite athlete, a bodybuilder — can have a BMI in the overweight or even obese range while carrying very low body fat and being in exceptional cardiovascular health.
BMI Does Not Measure Where Fat Is Carried. Visceral fat — fat stored around the abdominal organs — is far more metabolically dangerous than subcutaneous fat stored under the skin around the hips and thighs.
BMI Is a Screening Tool, Not a Diagnosis. A BMI result outside the normal range is a signal to investigate further — not a diagnosis of any health condition.
| Height | Healthy Weight Range (BMI 18.5–24.9) |
|---|---|
| 5ft 0in (152cm) | 44.9 – 60.5kg (99 – 133lbs) |
| 5ft 2in (157cm) | 47.8 – 64.4kg (105 – 142lbs) |
| 5ft 4in (163cm) | 49.9 – 67.3kg (110 – 148lbs) |
| 5ft 6in (168cm) | 52.2 – 70.3kg (115 – 155lbs) |
| 5ft 8in (173cm) | 55.3 – 74.4kg (122 – 164lbs) |
| 5ft 10in (178cm) | 58.5 – 78.7kg (129 – 173lbs) |
| 6ft 0in (183cm) | 61.8 – 83.2kg (136 – 183lbs) |
| 6ft 2in (188cm) | 65.2 – 87.8kg (144 – 194lbs) |
| 6ft 4in (193cm) | 68.7 – 92.5kg (152 – 204lbs) |
⚠️ Note on BMI and Body Image: BMI is a population-level statistical tool that says nothing about your worth, your character, your fitness, your habits, or your value as a person. It is one data point among many, and it is an imperfect one. If you are struggling with your relationship with food, your body, or your weight, please reach out to a healthcare provider or registered dietitian.
Yes. This online BMI calculator is 100% free with no registration, no subscription, and no payment required. Calculate your BMI as many times as you like at no cost.
According to WHO guidelines, a BMI between 18.5 and 24.9 is considered the normal weight range for adults. However, healthy BMI ranges vary by age, sex, ethnicity, and individual body composition — always discuss your result with your doctor.
No — this is one of BMI's most significant limitations. Athletes and highly muscular individuals frequently have BMI scores in the overweight or obese range despite having low body fat and excellent cardiovascular health. Body fat percentage, waist circumference, and other measures are more meaningful for muscular individuals.
This calculator is designed for adults aged 18 and over. BMI in children and teenagers is interpreted using age-specific and sex-specific percentile charts — not the adult category cut-offs. For children, please consult a paediatrician.
The BMI formula is identical for men and women and the standard WHO weight categories apply to both sexes equally. However, men and women naturally differ in body fat distribution and healthy body fat percentage ranges — meaning that the same BMI score can represent slightly different health situations.
A BMI of 30.0 or above is classified as obese according to standard WHO guidelines. Obesity is further divided into three classes — Class I (30–34.9), Class II (35–39.9), and Class III (40 and above) — each associated with progressively higher health risk.
No. A privacy-respecting BMI calculator processes your height and weight inputs locally in your browser and does not store, transmit, or log your personal health data anywhere. Your information remains completely private on your device.
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