BMI Calculator
Body Mass Index with WHO categories, ethnicity-adjusted thresholds, and a healthy weight range for your height.
How to use
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Start in Quick mode: just height and weight. The calculator shows your BMI, the WHO category, and your healthy weight range.
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If you want a more accurate picture, switch to Detailed mode. Add your age, sex, ethnicity, activity level and optionally your waist circumference.
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Detailed mode adjusts the BMI thresholds for ethnicity — South Asians and East Asians register as overweight at BMI 23 instead of 25 because of the way fat distributes — and pairs your BMI with the waist-to-height ratio.
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The 'What this means' section under the result is personalised to your inputs: age, activity level, ethnicity and waist all change the interpretation.
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BMI is a screening tool, not a diagnosis. Use this as one data point for a doctor's review, not the final word on your health.
Frequently asked questions
WHO defines 18.5 to 24.9 as normal weight for adults. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or higher is obese (split into three classes for severity). Detailed mode adjusts these for ethnicity and age.
Research from the UAE and South Asia shows people of Indian, Pakistani, Bangladeshi and Sri Lankan ancestry carry more visceral abdominal fat at the same BMI as Europeans. The WHO Asian-Pacific consultation (2004) recommended lower thresholds: overweight at 23 instead of 25, obese at 27.5 instead of 30. Detailed mode applies these adjusted thresholds when you select a South or East Asian ancestry.
No. BMI doesn't distinguish muscle from fat. A muscular rugby player can register as obese on standard BMI despite having 8% body fat. The Detailed mode flags this when you select 'Athlete' activity level — body fat percentage or a DEXA scan is more accurate for body composition assessment.
Waist circumference divided by height. The current evidence base suggests it's a stronger predictor of cardiometabolic disease than BMI alone. The simple rule: keep your waist below half your height. A 170 cm person's waist should stay under 85 cm. Above 0.5 means increased risk regardless of BMI. The Detailed mode shows your ratio if you measure your waist.
Not necessarily. A large body of evidence shows people over 65 with a BMI of 24-29 have lower mortality than those in the strict 'normal' range. Slightly higher weight protects against sarcopenia (muscle loss) and helps recovery from illness. Detailed mode flags this for users over 65.
Most BMI calculators apply one set of thresholds for everyone, regardless of age, ethnicity or activity. The Liphyr calculator's Detailed mode adjusts for South Asian and East Asian ancestry (the WHO Asian-Pacific guidelines), flags the U-shaped mortality curve for older adults, and pairs BMI with waist-to-height ratio. Same simple Quick mode if you just want the basic number.
Stand relaxed, exhale gently, measure at the natural narrowest point (usually just above the belly button, halfway between the bottom of your ribs and the top of your hip bone). Use a flexible tape measure parallel to the floor. Don't suck in. Take the measurement twice and use the average.
Yes, slightly. Weight fluctuates 1-2 kg through the day from food, water and waste. For consistent measurement: weigh yourself in the morning, after using the bathroom, before eating or drinking, naked or in light underwear. Weekly averages are more useful than daily readings.
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Source: WHO Asian-Pacific Region BMI consultation (2004), WHO 1997 classification, Royal College of Physicians UK 2013 ethnicity guidance · Last verified 2026-06. Verify on WHO. This tool provides estimates only and is not legal, tax or financial advice. Always verify your specific situation with the relevant UAE authority or a licensed advisor before taking action.