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Health, Fitness & Metabolic Calculators

Optimize your physical wellness and training targets with validated clinical formulas. Compute body mass index, basal metabolic energy expenditure, running marathon splits, and pregnancy gestational age.

26 Dedicated Tools• 100% In-Browser Privacy• Instant Formulas & Worked Examples

Available Health & Fitness Calculators

BMI (Body Mass Index) Calculator

Popular

Official WHO metric and imperial weight category index

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Calorie, TDEE & Macro Deficit Calculator

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Daily calories for fat loss, muscle gain & macro splits

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Running Pace & Marathon Split Calculator

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Calculate min/mile and min/km splits for 5K to 26.2 marathons

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Pregnancy Due Date & Trimester Timeline

Popular

Estimated delivery date and gestational development calendar

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Sobriety & Recovery Milestone Tracker

Track clean days, health milestones & financial savings

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Rehab Cost & Treatment Estimator

Estimate detox, inpatient, and outpatient recovery expenses

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Body Fat Percentage Calculator (US Navy Method)

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Calculate body fat percentage and fat vs lean mass using circumference measurements

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Basal Metabolic Rate (BMR) Calculator

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Calculate resting daily calories burned at complete physical rest

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Ideal Body Weight Calculator

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Compare ideal body weight estimates using Devine, Robinson, and Miller formulas

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Lean Body Mass (LBM) Calculator

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Calculate lean tissue weight and fat mass using Boer and James equations

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Ovulation & Fertility Window Calculator

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Calculate estimated ovulation day, fertile window, and next menstrual cycle

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Conception Date Calculator

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Estimate the exact conception date based on due date, ultrasound, or last period

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Menstrual Period & Cycle Tracker

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Predict your next 3 menstrual periods and PMS symptom phases

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Pregnancy Weight Gain Calculator

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Track healthy gestational weight gain guidelines by trimester

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One Rep Max (1RM) Calculator

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Calculate 1RM strength and training percentage percentages across Brzycki, Epley, and Lombardi formulas

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Target Heart Rate & Training Zones Calculator

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Calculate aerobic, anaerobic, and VO2 max heart rate zones using the Karvonen method

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Blood Alcohol Content (BAC) Calculator

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Calculate estimated blood alcohol concentration and sober-up timeline using Widmark's formula

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Macronutrient Split Calculator

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Calculate daily protein, carbohydrate, and fat targets for cutting, bulking, or maintaining

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Daily Protein Requirement Calculator

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Calculate optimal protein intake in grams for muscle building, endurance, or fat loss

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Daily Water Intake & Hydration Calculator

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Calculate optimal daily fluid intake based on body weight, climate, and exercise

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Body Type & Shape Calculator

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Determine body frame shape and Waist-to-Hip Ratio (WHR) health risk

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Calories Burned by Activity Calculator

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Calculate calories burned across 20+ sports using Metabolic Equivalent (MET) scores

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Intermittent Fasting Schedule Calculator

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Calculate eating and fasting windows for 16:8, 18:6, 20:4, and OMAD diets

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GFR Kidney Function Calculator (CKD-EPI)

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Calculate estimated Glomerular Filtration Rate (eGFR) and kidney disease staging

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Caffeine Half-Life & Sleep Clearance Calculator

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Calculate remaining caffeine in your bloodstream and optimal cutoff time for sleep

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REM Sleep Cycle & Bedtime Calculator

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Calculate optimal wake-up times and bedtimes based on 90-minute REM cycles

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Underlying Mathematical Logic

Mifflin-St Jeor Metabolic Energy Formula

Basal Metabolic Rate (BMR) is calculated via Mifflin-St Jeor: For Men: BMR = (10 × weight_kg) + (6.25 × height_cm) – (5 × age) + 5. For Women: BMR = (10 × weight_kg) + (6.25 × height_cm) – (5 × age) – 161. Total Daily Energy Expenditure (TDEE) multiplies BMR by physical activity level.

Frequently Asked Questions

How accurate is the BMI calculator for athletes and muscular individuals?

BMI is an epidemiological screening tool based on weight and height. It does not differentiate between lean muscle mass and adipose tissue; bodybuilders and strength athletes often rank as "overweight" or "obese" despite having very low body fat percentages.

How many calories should I cut to lose 1 pound of fat per week?

One pound of human adipose tissue represents approximately 3,500 calories. A daily caloric deficit of 500 kcal below your Total Daily Energy Expenditure (TDEE) produces approximately 1 pound (0.45 kg) of fat loss per week.

How is pregnancy due date estimated?

Using Naegele's rule, due date is estimated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP), assuming a standard 28-day menstrual cycle.

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