20 free calculators, no signups
Free Health & Fitness Calculators
Every calculator uses real formulas — Mifflin-St Jeor for calories, the Navy method for body fat, Karvonen for heart rate zones, Widmark for BAC. No signups, no tracking, no ads. Your numbers stay on your device.
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Body Composition
- Body CompositionBMI CalculatorFree BMI calculator with a visual chart, WHO category ranges, and context on what BMI actually tells you about health.Open calculator →
- Body CompositionBody Fat %Estimate body fat percentage from waist, neck, and hip measurements using the U.S. Navy circumference method.Open calculator →
- Body CompositionIdeal WeightCompute your healthy weight range using multiple formulas (Devine, Robinson, Hamwi, BMI 18.5–24.9) for height, frame, and sex.Open calculator →
- Body CompositionWaist-to-HipCalculate your waist-to-hip ratio (WHR) — a stronger predictor of metabolic risk than BMI — with WHO risk categories.Open calculator →
Nutrition & Hydration
- Nutrition & HydrationCalorie CalculatorCalculate your daily calorie needs (TDEE) using Mifflin-St Jeor with activity multipliers for cutting, maintaining, or bulking.Open calculator →
- Nutrition & HydrationMacro CalculatorCalculate protein, carbs, and fat in grams based on your calories and goal — cutting, maintaining, or building muscle.Open calculator →
- Nutrition & HydrationWater IntakeSee how many ounces of water you actually need per day based on body weight, activity level, and climate.Open calculator →
- Nutrition & HydrationProtein IntakeCalculate daily protein needs (grams) based on body weight, activity level, and goal — maintenance, muscle building, or cutting.Open calculator →
- Nutrition & HydrationIntermittent FastingSchedule your 16:8, 18:6, 20:4, or OMAD eating window from a last-meal time. See exactly when your fast ends.Open calculator →
- Nutrition & HydrationVitamin DEstimate daily vitamin D intake needs (IU) based on age, body weight, and sun exposure — with deficiency risk context.Open calculator →
Fitness & Training
- Fitness & TrainingHeart Rate ZonesCalculate your 5 training heart rate zones using the Karvonen formula — age, resting heart rate, and max HR accounted for.Open calculator →
- Fitness & TrainingWalking CaloriesCalculate calories burned walking by distance, pace, and body weight using MET values — treadmill, outdoor, or incline.Open calculator →
- Fitness & TrainingRunning PaceCalculate finish time from pace, pace from finish time, and splits for 5K, 10K, half marathon, and marathon distances.Open calculator →
- Fitness & TrainingOne Rep MaxEstimate your one-rep max from submaximal lifts using Epley, Brzycki, and Lombardi formulas — with a full %1RM percentage table.Open calculator →
Sleep & Recovery
Women's Health
- Women's HealthPregnancy Due DateEstimate your pregnancy due date from your last menstrual period (Naegele's rule) or conception date, with a full week-by-week timeline.Open calculator →
- Women's HealthOvulation CalculatorEstimate ovulation day and your 6-day fertile window from the first day of your last period and cycle length.Open calculator →
Wellness & Risk
- Wellness & RiskBlood PressureEnter systolic and diastolic readings to see your ACC/AHA blood pressure category, what it means, and when to act.Open calculator →
- Wellness & RiskBAC / Sober-UpEstimate blood alcohol content (BAC) using the Widmark formula and see how long until your BAC returns to zero.Open calculator →
- Wellness & RiskStress ScoreTake a 10-question stress assessment based on the Perceived Stress Scale and get a score with tailored recommendations.Open calculator →
Where should you start?
If you're trying to lose fat, build muscle, or just eat better, start with the TDEE calculator then the macro split. For a full body snapshot: BMI, body fat %, and waist-to-hip ratio. If your sleep is off, try the sleep-cycle timer. Runners and lifters go to pace and 1RM.
Everything here is for education. None of it replaces a conversation with a doctor, dietitian, or coach who knows you personally.