Health & Fitness Calculators: BMI, BMR, TDEE, Macros

These calculators turn a few body measurements into practical numbers you can act on: your Body Mass Index category, the calories you burn at rest (BMR) and across a normal day (TDEE), a protein and macro target for your goal, and estimates such as US Navy body fat percentage or ideal body weight.

We use the equations most widely cited in clinical and sports-nutrition literature — the WHO/CDC BMI thresholds, the Mifflin–St Jeor equation for BMR, standard activity multipliers for TDEE, and the Devine, Robinson, Miller, and Hamwi ideal-weight formulas. Each tool page explains the formula, shows a worked example, and lists its limitations (for example, BMI does not distinguish muscle from fat).

Use the results as a starting point for conversations with a healthcare professional, not as a diagnosis. Small daily changes based on reliable estimates beat big changes based on guesses.

All health & fitness calculators

Pick a tool to see the calculator, formula, worked example, and FAQs.

Health BMI Calculator Body Mass Index and weight category. Health Protein Calculator Daily protein needs by goal & activity. Health BMR Calculator Basal Metabolic Rate (Mifflin-St Jeor). Health TDEE Calculator Total Daily Energy Expenditure + cut/bulk. Health Ideal Weight Healthy BMI range + Hamwi, Devine, Robinson, Miller averages. Health Water Intake Recommended daily water intake. Health Macro Calculator Split calories into P/C/F grams. Health Body Fat (US Navy) Body fat % from measurements. Health One-Rep Max Estimate 1RM from weight × reps. Health Running Pace Pace per km/mile from distance & time. Health Sleep Cycle Bedtime Best bedtimes for 90-minute cycles. Health Pregnancy Due Date Estimate due date from LMP.

Sources & methodology

Formulas and conversion factors in this section follow:

Health and fitness results are estimates for general education and planning. They are not medical advice and do not replace an assessment by a doctor, registered dietitian, or other qualified professional.

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