Health Tools
6 free tools — precise calculations, instant results.
bmi
Launch tool
calorie
Launch tool
age calculator
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ideal weight
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body fat
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pregnancy due date
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About Health Tools
Health calculators help you estimate BMI, body fat percentage, calorie needs, ideal weight, age, and pregnancy due dates. All calculations follow WHO, CDC, and peer-reviewed medical guidelines. These tools are for reference—always consult a healthcare professional for medical decisions.
Body Mass Index (BMI): What It Measures and Its Limits
BMI is calculated as weight (kg) ÷ height² (m²). The WHO classifies BMI under 18.5 as underweight, 18.5–24.9 as normal, 25–29.9 as overweight, and 30+ as obese. BMI is a population-level screening tool—it does not differentiate between muscle and fat, which means highly muscular athletes often register as 'overweight'. It also varies by ethnicity—Asian populations have higher health risks at lower BMI values.
Calorie Needs: BMR and TDEE
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to sustain basic functions. It is calculated using the Mifflin-St Jeor equation: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + (5 for men, −161 for women). Your Total Daily Energy Expenditure (TDEE) multiplies your BMR by your activity level factor (1.2 for sedentary, 1.725 for very active).
Body Fat Percentage: A More Complete Picture
Body fat percentage measures the proportion of fat mass to total body mass. Healthy ranges differ by sex: essential fat is 2–5% for men and 10–13% for women. Athletes typically have 6–13% (men) or 14–20% (women). The U.S. Navy Method estimates body fat from waist, neck, and hip measurements without expensive equipment. It is less accurate than DEXA scans but sufficient for general health monitoring.
Frequently Asked Questions
What is a healthy BMI range?
The WHO considers 18.5–24.9 to be a healthy BMI range for adults. However, these thresholds are adjusted for different ethnic populations—Asian adults face increased health risks at BMI 23+.
How many calories do I need per day?
Average adult calorie needs range from 1,600–2,400 kcal/day for women and 2,000–3,000 kcal/day for men, depending on age, height, weight, and activity level. Use the calorie calculator for a personalized estimate.
Can I trust online health calculators?
Online health calculators provide evidence-based estimates, not medical diagnoses. They are useful for general awareness and tracking trends over time. Always consult a doctor before making health decisions.