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BMI calculator

Calculate your body mass index in seconds. Discover your category and ideal weight based on WHO standards.

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What is BMI?

Body mass index (BMI) is a simple indicator that relates your weight to your height. Developed by mathematician Adolphe Quetelet in the 19th century and adopted by the World Health Organization (WHO), it provides a quick way to assess whether a person is underweight, at a normal weight, overweight or obese. The formula is simple: BMI = weight (kg) / height (m) squared. It's the most widely used screening tool in the medical world.

BMI limitations you should know

BMI doesn't distinguish fat mass from muscle mass. A muscular athlete can have a high BMI without being overweight. Likewise, an older person with little muscle can have a normal BMI while carrying too much body fat. BMI also doesn't account for fat distribution (abdominal vs. peripheral), which is an important risk factor. It's a useful first-line indicator, but not a diagnosis on its own.

BMI categories according to the WHO

The WHO defines several categories: underweight (BMI < 18.5), normal weight (18.5-24.9), overweight (25-29.9), moderate obesity (30-34.9), severe obesity (35-39.9) and morbid obesity (>40). These thresholds are the same for adult men and women. For children and adolescents, specific growth charts are used. Normal weight corresponds to the range associated with the lowest risk of health complications.

What to do after calculating your BMI

BMI gives you a starting point. If your result is outside the normal range, the first step is understanding your current calorie intake. Nutritional tracking with Kalo lets you see exactly what you're eating every day, effortlessly. From there, you can gradually adjust your eating habits to move closer to your ideal weight.

Frequently asked questions

How do you calculate your BMI?
BMI is calculated by dividing your weight in kilograms by your height in meters squared. For example, for 70 kg and 1.75 m: 70 / (1.75 x 1.75) = 22.9. Our calculator does this calculation automatically.
What is the ideal BMI?
According to the WHO, a BMI between 18.5 and 24.9 is considered normal and associated with the lowest risk of weight-related health problems. The ideal also depends on individual factors like muscle mass and body type.
Is BMI reliable for athletes?
BMI has its limits for muscular athletes. Since muscle is denser than fat, an athlete can have a high BMI (>25) without excess fat. For these profiles, additional measurements like waist circumference or body fat percentage are more relevant.
Is BMI the same for men and women?
Yes, WHO thresholds are identical for adults of both sexes. However, women naturally have a higher body fat percentage than men for the same BMI.
How often should you recalculate your BMI?
If you're following a nutrition or training program, a monthly calculation is enough to track progress. The key is combining BMI with other indicators: waist circumference, energy levels, and daily food tracking.

Take action with Kalo

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