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TallyBench / BMI Calculator
// 04 · BMI CALCULATOR

Body mass index from height and weight.

Enter your height in centimeters or feet and inches, plus your weight in kilograms, to get your BMI and category instantly.

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Category

How is BMI calculated?

BMI is weight in kilograms divided by height in meters squared. Switch the height unit dropdown to feet & inches if that's easier to enter — it's converted to meters automatically either way.

Is BMI an exact health measurement?

No. BMI is a screening estimate based on height and weight only — it doesn't account for muscle mass, bone density, age, or frame size, so treat the category as a starting point, not a diagnosis. For a full picture, a doctor considers other factors alongside it.

What are the standard BMI categories?

Under 18.5 is generally classed as underweight, 18.5–24.9 as a healthy range, 25–29.9 as overweight, and 30+ as obese, per the commonly used adult thresholds.

Does BMI apply the same way to children and teenagers?

No — BMI for anyone under 20 is interpreted using age- and sex-specific percentile charts, not the fixed adult categories this calculator uses. A pediatrician's growth chart is the correct tool for a child or teen's BMI, not this calculator.

Does this calculator account for athletes or very muscular people?

No — BMI can't distinguish muscle from fat, so a muscular person can show as 'overweight' despite having low body fat. Body fat percentage or waist-to-height ratio are better measures in that specific case.

Worked example: a person who is 175cm tall and weighs 72kg has a BMI of 72 ÷ (1.75×1.75) = 72 ÷ 3.0625 ≈ 23.5, which falls in the healthy range (18.5–24.9).