TetraKits
Calculate Body Mass Index with gender, age, and metric or US/UK units. See BMI category, health risk level, healthy weight range, adult and child CDC reference tables, and an interactive chart. The TetraKits BMI Calculator runs entirely in your browser — free, private, and ready on mobile or desktop.
Overview
Health questionnaires, fitness tracking, and pediatric checkups reference BMI — but adult and child interpretations differ. This calculator handles both with CDC categories, healthy weight ranges, and unit flexibility.
How to use the bmi calculator
- Enter gender, age, and units — Select male or female, enter age (2–120), and choose US/UK (feet/inches, pounds) or metric (cm, kg).
- Enter height and weight — Type your measurements. BMI = weight (kg) ÷ height (m)². Results update instantly as you type.
- Read category and healthy range — See BMI value, WHO/CDC category, and the weight range for BMI 18.5–24.9 at your height. Track age with the age calculator.
Common use cases
- Enter gender, age, and units: Select male or female, enter age (2–120), and choose US/UK (feet/inches, pounds) or metric (cm, kg).
- Enter height and weight: Type your measurements.
- Read category and healthy range: See BMI value, WHO/CDC category, and the weight range for BMI 18.
- Bookmark for quick access: Save the tool for repeat tasks without installing an app.
Frequently asked questions
What is a healthy BMI for adults?
WHO classifies 18.5–24.9 kg/m² as normal weight for adults age 20 and older. Below 18.5 is underweight; 25+ is overweight.
How is BMI different for children?
For ages 2–19, BMI is compared to CDC growth chart percentiles by age and sex — not fixed adult cutoffs.
Is BMI accurate for athletes?
Muscular individuals may have higher BMI without excess fat. Use BMI as one screening tool alongside professional advice.
What healthy weight should I target?
The calculator shows the weight range that corresponds to BMI 18.5–24.9 at your height.
Is this BMI calculator free?
Yes. Free with unlimited calculations and no signup; health data stays on your device.
