BMI Calculator
Calculate your Body Mass Index and check if your weight is in a healthy range.
Use Tool →Health & Fitness
Calculate health metrics using formulas from trusted medical sources. Our BMI calculator uses the standard WHO formula with CDC classification thresholds. Calorie and macro calculators reference peer-reviewed equations like Mifflin-St Jeor and USDA dietary guidelines. Your health data stays completely private—processed only in your browser.
Each tool targets a specific health metric. The BMI calculator applies the WHO classification system with standard thresholds for underweight, normal, overweight, and obese categories. The calorie calculator uses the Mifflin-St Jeor equation, published in 1990 and considered the gold standard by the Academy of Nutrition and Dietetics (AND), with activity-level multipliers for sedentary through very active lifestyles. The macro calculator distributes calories across protein, carbohydrates, and fat. The body fat calculator estimates body composition using the U.S. Navy circumference-based method.
It is important to understand that these tools provide estimates based on population-level formulas. BMI does not account for muscle mass, bone density, or overall body composition, which means athletic individuals may be misclassified. The WHO explicitly notes that BMI is a screening tool, not a diagnostic measure. Calorie and macro estimates vary with individual metabolism. Always consult a qualified healthcare professional before making medical or dietary decisions. All data stays in your browser and is never transmitted.
Calorie Calculator
Calculate your daily calorie needs (TDEE) based on age, gender, weight, height, and activity level.
Use Tool →Macro Calculator
Calculate your daily protein, carbs, and fat intake based on your calorie goals and preferred diet type.
Use Tool →Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy method with simple body measurements.
Use Tool →Gestational Age Calculator
Calculate gestational age, estimated due date, and pregnancy milestones from your last menstrual period.
Use Tool →Frequently Asked Questions
How is BMI calculated?
BMI (Body Mass Index) is calculated by dividing weight in kilograms by height in meters squared: BMI = kg/m². The formula was developed by Adolphe Quetelet in 1832 and is used by the WHO to classify weight categories: underweight (below 18.5), normal (18.5–24.9), overweight (25–29.9), and obese (30 and above).
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation (published in 1990) estimates Basal Metabolic Rate (BMR), the calories your body needs at rest. It is considered more accurate than the older Harris-Benedict equation by the Academy of Nutrition and Dietetics. Our calorie calculator uses this equation along with activity multipliers to estimate total daily energy expenditure.
Is my health data kept private?
Yes, all health calculations run entirely in your browser. No personal data—including weight, height, age, or body measurements—is ever sent to any server. There is no account required, no tracking, and no data collection.
What is the U.S. Navy body fat method?
The U.S. Navy body fat method estimates body fat percentage using circumference measurements. For men, it uses neck and waist measurements; for women, it adds a hip measurement. The formulas are based on the Hodgdon and Beckett equations, developed in 1984 and adopted by the U.S. Department of Defense for fitness assessments. While less precise than laboratory methods like DEXA scans or hydrostatic weighing, it is widely accepted as a practical field method because it requires only a tape measure. Our body fat calculator implements these equations with results comparable to standard Navy fitness screening.
What are recommended macronutrient ratios?
The National Academy of Medicine defines Acceptable Macronutrient Distribution Ranges (AMDR) for healthy adults: protein should provide 10–35% of total daily calories, carbohydrates 45–65%, and fat 20–35%. These ranges support adequate nutrient intake while reducing the risk of chronic disease. Athletes and individuals with specific goals may adjust these ratios — for example, higher protein intake (1.6–2.2 g/kg body weight) is often recommended for muscle building. Our macro calculator lets you set custom percentage splits or choose from common presets like balanced, low-carb, or high-protein distributions.