Adult BMI Calculator estimates Body Mass Index using the standard adult formula and shows your category, a healthy weight range for your height, and weight-to-target guidance. The method follows widely accepted clinical cutoffs used in public health. For reference, see the World Health Organization’s summary of adult BMI and categories: WHO: Obesity and Overweight.

How to use this calculator

  1. Select units: Metric (kg, cm) or US (lb, ft+in).
  2. Enter weight and height. For US, type feet and inches separately.
  3. Press “Calculate BMI.” You’ll see your BMI value, category, healthy range, and how much to gain or lose to reach the normal range.

Formula and categories

  • Formula (metric): BMI = weight(kg) / [height(m)]²
  • Formula (US): BMI = 703 × weight(lb) / [height(in)]²

Adult categories (ages ≈20+): Underweight <18.5; Normal 18.5–24.9; Overweight 25.0–29.9; Obesity ≥30 (class I 30–34.9, class II 35–39.9, class III ≥40).

Outputs you’ll get

  • BMI value to two decimals and your category.
  • Healthy weight range (the weights that yield BMI 18.5–24.9 at your height).
  • Target guidance: how much weight to gain or lose to enter the normal range.
  • Automatic unit conversion so you can read results in either system.

Why this calculator is reliable

  • Uses the official adult BMI formulas and standard public-health cutoffs.
  • Computes the healthy range directly from those cutoffs for your exact height.
  • Handles US feet+inches correctly by summing total inches before calculation.
  • Shows conversions to avoid unit mistakes.

Interpretation tips

  • BMI is a screening tool, not a diagnosis. It correlates with population risk but does not measure body fat directly.
  • At the same BMI, body-fat % may differ by age, sex, and ethnicity.
  • Not appropriate for pregnancy, very muscular athletes, or certain clinical conditions.
  • Children and teens require age- and sex-specific BMI-for-age charts, not adult cutoffs.

Examples

  • Metric: 70 kg and 175 cm → height 1.75 m → BMI = 70 / 1.75² = 22.86 (Normal). Healthy range ≈ 56.7–76.3 kg.
  • US: 180 lb and 5 ft 9 in → total 69 in → BMI = 703×180 / 69² = 26.6 (Overweight). Healthy range ≈ 125.6–169.1 lb.

What is your body mass index and how well you feel yourself in your current body? Let us know in the comments!

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