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BMI Calculator

Calculate your Body Mass Index in metric (cm/kg) or imperial (ft+in/lbs) units. See your BMI category, healthy weight range, and a visual scale showing where you fall.

BMI

22.9

Normal weight

15 — Underweight18.5253040+

Healthy Weight Range

56.7 – 76.3 kg

BMI is a general indicator and does not account for muscle mass, age, sex, or body composition. Consult a healthcare provider for personalized health guidance.

Understanding BMI

Body Mass Index (BMI) was developed in the 1830s by Belgian statistician Adolphe Quetelet as a population-level measure, not an individual diagnostic tool. It became widely used in medicine because it's quick and requires only height and weight — two measurements anyone can take without specialized equipment.

The formula: BMI = kg ÷ m² (metric) or BMI = (lbs ÷ in²) × 703 (imperial). Verification: 70kg, 175cm → 70 ÷ 3.0625 = 22.9 (Normal weight).

BMI is a starting point, not a complete picture. For a more accurate assessment of body composition, healthcare providers may also measure waist circumference, body fat percentage, blood pressure, cholesterol, and blood sugar. Always consult a healthcare professional for health assessments.

BMI Calculator FAQs

How is BMI calculated?
BMI = weight (kg) ÷ height (m)². For imperial: BMI = (weight in lbs ÷ height in inches²) × 703. For example, a person 175cm tall weighing 70kg has BMI = 70 ÷ (1.75)² = 70 ÷ 3.0625 = 22.9.
What BMI is considered healthy?
For adults: Underweight = below 18.5, Normal weight = 18.5–24.9, Overweight = 25–29.9, Obese = 30 and above. These categories are the same for men and women, though the interpretation may differ by age and other factors. BMI ranges for children use different percentile-based thresholds.
Is BMI accurate?
BMI is a useful screening tool but has significant limitations. It does not distinguish between fat and muscle mass — a muscular athlete might have a "high" BMI but low body fat. It also doesn't account for age, sex, ethnicity, or where fat is distributed. A high BMI is associated with increased health risks, but BMI alone cannot diagnose health status.
What is a healthy weight for my height?
This calculator shows the healthy weight range for your height (BMI 18.5–24.9). For example, a 175cm (5'9") person's healthy weight range is approximately 56.5–76.5 kg (125–169 lbs). These are population-level guidelines, not individual targets.
Does BMI apply to children?
Children's BMI is calculated the same way but interpreted differently using age- and sex-specific percentiles. A child is considered "healthy weight" if BMI falls between the 5th and 85th percentile for their age and sex. This calculator is designed for adults (18+).
What is BMI used for?
BMI is used by healthcare providers as a quick screening tool to categorize patients and identify potential health risks. It is also used in population-level research. While not a diagnostic tool, a BMI outside the normal range typically prompts further investigation using more detailed measures.

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