Health Calculators
From BMI and calorie needs to pregnancy timelines and blood pressure — our free health calculators give you clear numbers based on validated formulas. All tools are for informational purposes; always consult a healthcare professional for medical decisions.
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Body & Weight
BMI, body fat, ideal weight, and waist-to-hip ratio
Nutrition & Calories
TDEE, BMR, macro targets, and calorie needs
Pregnancy & Fertility
Due date, ovulation, conception, and fertility tracking
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Health Glossary — Key Terms Explained
- BMI (Body Mass Index)
- A measure of body mass relative to height: BMI = weight (kg) ÷ height (m)². Ranges: Underweight <18.5, Normal 18.5–24.9, Overweight 25–29.9, Obese ≥30. Does not account for muscle mass or body composition.
- BMR (Basal Metabolic Rate)
- The number of calories your body burns at complete rest to maintain basic functions (breathing, circulation, cell repair). The foundation of all calorie calculations.
- TDEE (Total Daily Energy Expenditure)
- BMR multiplied by an activity factor. Your TDEE is the total calories you burn per day including all movement and exercise.
- Macronutrients
- The three calorie-providing nutrients: protein (4 kcal/g), carbohydrates (4 kcal/g), and fat (9 kcal/g). Alcohol provides 7 kcal/g but is not a macronutrient.
- WHO BMI Classification
- The World Health Organization's standard BMI categories: Underweight (<18.5), Normal weight (18.5–24.9), Pre-obesity/Overweight (25–29.9), Obesity class I (30–34.9), II (35–39.9), III (≥40).
Frequently Asked Questions
What is a healthy BMI?
The WHO defines healthy BMI as 18.5–24.9 kg/m². However, BMI doesn't distinguish between muscle and fat. Athletes with high muscle mass may have a BMI in the 'overweight' range with very low body fat. Asian populations may face health risks at lower BMI thresholds (23+).
How many calories do I need per day?
The average adult needs 1,600–3,000 calories per day depending on sex, age, weight, height, and activity level. Women typically need 1,600–2,400 kcal; men 2,000–3,000 kcal. Use the TDEE calculator with your specific stats for an accurate personal estimate.
Are health calculators accurate?
Health calculators use validated population-average formulas. Individual results vary by 10–20% from actual values due to metabolic differences, body composition, and measurement accuracy. They're best used as starting points and compared against how you feel and respond.
When should I see a doctor instead of using a calculator?
Always consult a healthcare professional for: symptoms of illness, unexplained weight changes, blood pressure readings consistently above 140/90, BMI below 17 or above 35, or for any condition affecting your health decisions. Calculators inform — they don't diagnose.