Health & Fitness Hub
34+ free science-backed health calculators and fitness tools. All calculations happen in your browser — no accounts, no data collection.
Water Intake Calculator
Get a personalized daily water goal based on your weight, activity level, climate, and health status. Includes a 12-slot hydration schedule and real-time tracker.
Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy formula and BMI method. Get your fat category, lean mass estimate, and health rating instantly.
Heart Rate Zones Calculator
Calculate your custom aerobic, anaerobic & fat-burn zones using Karvonen, Tanaka & Gellish formulas. Generate downloadable report handouts.
Hydration
1Body Composition
8U.S. Navy & BMI methods to estimate body fat percentage accurately
Body Mass Index calculator with healthy range analysis
Find your ideal weight based on height and frame size
Estimate lean muscle mass and track your fitness progress
Compare clinical ideal weights side-by-side using Devine, Robinson, and Miller equations
Verify military compliance tape-test standards under AR 600-9 rules
Calculate medical BSA parameters with Mosteller, DuBois, and Haycock equations
Identify your somatic body outline using chest, waist, and hip ratios
Pregnancy & Women's Health
5Calculate due date, weeks, gestational age, and fetal development milestones
Estimate fertilization date, fertile window, and gestational milestones
Track healthy week-by-week weight gain bounds based on pre-pregnancy BMI
Forecast ovulation cycles, ovulation windows, and cycle milestones
Estimate upcoming menstrual cycles and track cycle regularity
Nutrition & Calories
9Estimate daily calories using Mifflin-St Jeor & Harris-Benedict. Set deficit/surplus goals & get macro splits
Total Daily Energy Expenditure calculator for weight goals
Basal Metabolic Rate — calories your body burns at complete rest
Protein, carbs & fat ratios tailored to your fitness goal
Detailed Katch-McArdle energy expenditure calculator based on activity factors
Determine daily protein requirements matching muscle mass goals
Compute daily dietary carbohydrate ranges for aerobic and lifestyle loading
Calculate optimal daily dietary lipid and healthy fat targets
Calculate energy burn rates over specific workout sessions
Medical & Vitals
6Calculate safe pediatric & adult medication doses by weight, age, and pre-existing conditions
Calculate pediatric drug doses using Young's, Clark's, and BSA rules
Calculate personalized training zones using Karvonen, Tanaka & Gellish formulas
Calculate aerobic, fat-burn & peak heart rate training zones
Analyze systolic/diastolic readings and hypertension risk
Estimate Blood Alcohol Concentration limits over time using Widmark models
Sleep & Workout Timers
5Estimate absolute muscular lift limits using scientific formulas
Calculate optimal bedtime & wake up times based on 90-min cycles
Calculate running pace, predict finish times, splits & training zones
High-intensity interval training timer with rest periods
Customizable work/rest intervals for any training style