Health Tools
Free health and fitness calculators using standard clinical formulas. BMI, TDEE, heart rate zones, sleep cycles, macros, and more. Results are wellness estimates only, not medical advice.
BMI Calculator
Calculate your Body Mass Index, see your weight category, and understand what it means — and what it misses.
TDEE / BMR Calculator
Find your daily calorie target for maintaining, losing, or gaining weight using the Mifflin-St Jeor formula.
Body Fat Calculator
Estimate body fat percentage using the US Navy circumference method — no scales or calipers needed.
Water Intake Calculator
Get a personalised daily water target based on your body weight, activity level, and climate.
Macro Calculator
Calculate daily protein, carbohydrate, and fat targets for your goal — balanced, low-carb, or keto.
Running Pace Calculator
Calculate your pace per mile or km and project finish times for 5K, 10K, half marathon, and marathon.
Target Heart Rate Calculator
Find all five training zones using the Karvonen heart rate reserve method for more effective workouts.
Sleep Cycle Calculator
Find the best times to wake up or fall asleep based on 90-minute cycles — wake refreshed, not groggy.
Calories Burned Calculator
Estimate calories burned across 15 common activities using MET values, body weight, and session duration.
Pregnancy Due Date Calculator
Calculate your estimated due date using Naegele's rule and track upcoming milestones by week.
Evidence-Based Health Metrics
Health calculators on this page use formulas from peer-reviewed research and guidelines from the CDC, WHO, NIH, and ACSM. BMI uses the Quetelet Index (kg/m²), validated in large population studies. TDEE calculations use the Mifflin-St Jeor equation, shown in clinical research to be more accurate than the earlier Harris-Benedict formula. Heart rate zones reference American Heart Association guidelines for aerobic training intensity.
What These Numbers Tell You
Health metrics are population-level averages, not individual diagnoses. BMI, for example, does not measure body fat directly — it estimates weight-to-height proportion and was designed for large-scale epidemiological studies, not clinical assessment of individuals. Similarly, TDEE estimates are accurate to within 10-20% for most people but vary based on gut microbiome, metabolic history, and activity measurement accuracy. Use these as starting points, not endpoints.
Important Medical Disclaimer
These calculators provide general health information for educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment. Consult a qualified healthcare provider before making changes to your diet, exercise program, or health regimen based on any calculator output. Pregnant individuals, those with chronic conditions, and anyone under medical supervision should always defer to their healthcare team.
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