Easy BMI Calculator for Adults — Underweight, Healthy, Overweight, Obese
What it is
A simple tool that computes Body Mass Index (BMI) from an adult’s height and weight to classify weight status.
How it works
- Input height (cm or ft/in) and weight (kg or lb).
- Calculator converts units if needed and uses BMI = weight(kg) / height(m)^2.
- Outputs BMI value (one decimal) and weight category.
Standard adult BMI categories
- Underweight: BMI < 18.5
- Healthy (Normal): 18.5–24.9
- Overweight: 25.0–29.9
- Obese: ≥ 30.0
Key features to include
- Unit selection and automatic conversion.
- Rounded BMI with category label and brief explanation.
- Visual indicator (color or gauge).
- Age and sex note: standard BMI categories apply to adults (≥20 years); different interpretations for older adults.
- Optional fields: waist circumference, body fat estimate, and activity level for added context.
- Accessibility and mobile responsiveness.
Limitations
- BMI does not distinguish fat vs. muscle, bone density, or fat distribution.
- Not reliable for athletes, pregnant people, children/teens, or very elderly without clinical context.
- Use as a screening tool, not a diagnostic test—consult a healthcare provider for personalized assessment.
Quick implementation (logic)
- Convert inputs to kg and meters.
- Calculate BMI and round to one decimal.
- Map to category using thresholds above.
- Display result, category, and one-line advice (e.g., “Consult a clinician for a full assessment”).
Example
Input: 70 kg, 1.75 m → BMI = 22.9 → Category: Healthy.