Free Health Calculators 2026 — BMI, TDEE, Calorie & Medical

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Health Calculators — BMI, TDEE, Dosage & Clinical Calculations

Health calculators help patients, caregivers, and healthcare professionals make data-driven decisions about nutrition, fitness, medication dosing, and clinical assessment. Every calculator on CalculatorCove uses formulas verified against CDC guidelines, NIH research, and peer-reviewed medical literature. All calculations run in your browser — your health data never leaves your device.

TDEE Calculator — Total Daily Energy Expenditure

Your TDEE (Total Daily Energy Expenditure) is the total calories your body burns each day including activity. It is calculated by multiplying your BMR (Basal Metabolic Rate) using the Mifflin-St Jeor formula by your activity factor. To lose weight, subtract 500 calories from your TDEE for approximately 1 pound of fat loss per week. Our TDEE Calculator gives you your exact calorie target for weight loss, maintenance, or muscle gain.

BMI Calculator — Body Mass Index

BMI (Body Mass Index) = weight (kg) ÷ height (m)². A BMI of 18.5 to 24.9 is healthy weight, 25 to 29.9 is overweight, and 30+ is obese. BMI is a screening tool — it does not account for muscle mass or body composition. Use it alongside body fat percentage and waist circumference for a complete picture. Our BMI Calculator supports both metric and imperial units.

Medical Dosage Calculators

Clinical dosage calculators help healthcare professionals calculate weight-based medication doses, IV drip rates, and unit conversions. Our dosage calculators cover mg/kg dosing, mg to mL conversion, and pediatric weight-based calculations. All formulas follow standard clinical pharmacology guidelines used in hospital settings.

Pregnancy and Fertility Calculators

Our pregnancy due date calculator uses Naegele’s rule (LMP + 280 days) to estimate your due date, trimester dates, and key milestones. Fertility calculators help identify your ovulation window based on cycle length. All pregnancy calculators include a disclaimer that results are estimates — your OB/GYN should confirm all dates via ultrasound.

Frequently Asked Questions

TDEE is calculated by multiplying your BMR (Basal Metabolic Rate) by your activity factor. Use the Mifflin-St Jeor formula for BMR: (10 x weight kg) + (6.25 x height cm) - (5 x age) + 5 for men, or -161 for women. Multiply by 1.2 (sedentary) to 1.725 (very active). Subtract 500 calories from TDEE to lose approximately 1 pound per week.

For adults, a BMI of 18.5 to 24.9 is considered healthy weight. A BMI of 25 to 29.9 is overweight. 30 to 34.9 is obese class I. 35 to 39.9 is obese class II. 40 or above is severely obese. BMI is a screening tool and does not account for muscle mass, bone density, or body composition.

Weight-based dosing: dose (mg) = prescribed dose (mg/kg) x patient weight (kg). For example, 10 mg/kg for a 70 kg patient = 700 mg. For liquid medications: volume (mL) = dose (mg) / concentration (mg/mL). Always verify calculations with a pharmacist or prescribing physician before administering any medication.

The standard method is Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). Alternatively, subtract 3 months and add 7 days to your LMP. The due date is an estimate — only about 5% of babies are born exactly on their due date. Your OB/GYN will confirm via ultrasound.

Essential fat is 2-5% for men and 10-13% for women. Athletes: 6-13% men, 14-20% women. Fitness: 14-17% men, 21-24% women. Average: 18-24% men, 25-31% women. Obese: 25%+ men, 32%+ women. Body fat percentage is a better health indicator than BMI because it distinguishes muscle from fat.

One pound of fat equals approximately 3,500 calories. To lose 1 pound per week, create a 500-calorie daily deficit. To lose 2 pounds per week, create a 1,000-calorie deficit. Do not go below 1,200 calories/day for women or 1,500 calories/day for men without medical supervision. Calculate your TDEE first, then subtract your target deficit.

Online health calculators using validated formulas (Mifflin-St Jeor for TDEE, standard BMI formula, Naegele's Rule for due dates) are accurate within 5-10% for most adults. Individual variation in metabolism, body composition, and health conditions means results are estimates. Always consult a healthcare provider for medical decisions.

For children and teenagers aged 2-19, BMI is assessed using age- and sex-specific percentiles. Below 5th percentile is underweight. 5th to 85th is healthy weight. 85th to 95th is overweight. 95th percentile or above is obese. Adult BMI cutoffs do not apply to children.

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