Health & Fitness Calculators
Your body is a system of inputs and outputs. Calories in, calories out. Heart rate up, recovery time down. BMI up, cardiovascular risk up. Health calculato...
120 calculators available · Updated 2026-06-15
Your body is a system of inputs and outputs. Calories in, calories out. Heart rate up, recovery time down. BMI up, cardiovascular risk up. Health calculators turn those relationships into numbers you can act on — and unlike a fitness tracker, they do not require a wearable, a subscription, or your data leaving the device. Every formula here is grounded in peer-reviewed research from WHO, NHS, NIH, and the Mayo Clinic, and updated when the underlying science changes.
How to choose the right health calculator
Start with a baseline. The BMI calculator gives you a quick weight-status category, but it is imperfect for athletes and muscle-dense individuals — pair it with the body fat percentage calculator for a fuller picture. The BMR (basal metabolic rate) tells you what your body burns at rest; the TDEE (total daily energy expenditure) adds your activity level on top of that. The calorie calculator uses both to give you a target for weight loss, maintenance, or muscle gain. For cardiovascular health, the target heart rate calculator defines your training zones, and the heart rate recovery calculator tracks aerobic fitness over time.
BMI, body composition, and weight status
BMI (body mass index) divides your weight in kilograms by the square of your height in meters. It is a population-level screening tool, not a diagnostic one. The healthy BMI range for adults is 18.5-24.9; for children and teens, BMI is interpreted as a percentile by age and sex. The adjusted body weight calculator is used clinically when BMI is high to estimate medication dosing weight. The body fat percentage calculator uses the US Navy circumference method, which is more accurate than BMI for muscular individuals. The waist-to-hip ratio calculator assesses central obesity, a stronger predictor of cardiovascular risk than BMI alone.
Calories, metabolism, and weight management
The BMR calculator uses the Mifflin-St Jeor equation, which is the most accurate for most adults. The Harris-Benedict equation is an alternative often used in clinical settings. The TDEE multiplier is 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active, and 1.9 for extra active. To lose weight, a 500-calorie daily deficit produces about 1 pound per week of fat loss; to gain, a 250-500 surplus. The macro calculator breaks your target calories into protein, fat, and carbohydrate grams based on your goal and training style.
Cardiovascular health and fitness
The target heart rate calculator uses the Karvonen formula: (220 - age) × intensity percentage. For fat burning, target 60-70% of max heart rate; for cardio fitness, 70-80%; for anaerobic threshold, 80-90%. The VO2 max calculator estimates your aerobic capacity from resting heart rate, age, and sex — a higher VO2 max is associated with lower all-cause mortality. The calories burned calculator uses METs (metabolic equivalents) for specific activities; walking is roughly 3.5-5 METs, running is 8-12 METs depending on pace.
Pregnancy, fertility, and life-stage calculations
The due date calculator uses the standard 280-day (40-week) gestation from the first day of your last menstrual period. The ovulation calculator estimates your fertile window based on a 28-day cycle average; the conception calculator works backward from a known due date. The pregnancy weight gain calculator gives week-by-week targets based on pre-pregnancy BMI. The pediatric BMI percentile calculator uses CDC growth charts to classify a child as underweight, healthy weight, overweight, or obese for their age and sex.
Methodology and safety
All health calculators are designed for informational purposes. They do not replace medical advice, diagnosis, or treatment from a qualified clinician. Formulas follow WHO, NHS, NIH, and peer-reviewed clinical sources. Units default to metric with imperial toggle where applicable. The healthy range column references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references/" class="font-medium text-slate-900 hover:text-slate-900 underline decoration-indigo-200 hover:decoration-indigo-500 underline-offset-2">references the WHO international BMI classification; the CDC classification is also shown for US users. Pregnancy calculators assume a 28-day cycle unless overridden. When in doubt, consult your physician.
Most Popular Health & Fitness Calculators
BMI
Body Mass Index from height and weight.
BMR
Basal metabolic rate — calories your body burns at rest.
TDEE
Total daily energy expenditure based on activity level.
Body Fat
Body fat % using the US Navy method.
Calorie
Daily calorie needs (TDEE) by activity level.
Target Heart Rate Calculator — 5 Zones | CalcxApp
Quick and accurate target heart rate calculator with visual charts and detailed tables.
Ovulation
Estimate fertile window.
BMI Percentile Calculator — Kids & Teens (CDC) | CalcxApp
Quick and accurate bmi percentile calculator with visual charts and detailed tables.
All Health & Fitness Calculators (120)
BMI
Body Mass Index from height and weight.
BMR
Basal metabolic rate — calories your body burns at rest.
TDEE
Total daily energy expenditure based on activity level.
Calorie
Daily calorie needs (TDEE) by activity level.
Water Intake
Daily water intake recommendation based on weight and activity.
Macro Calculator
Daily macronutrient targets based on goals and activity.
Protein Intake
Daily protein recommendation based on weight and activity.
Pregnancy Weight Gain
Recommended weight gain range during pregnancy by BMI.
Due Date
Estimate your delivery due date from the last menstrual period.
Conception Date
Estimate the likely conception date from a due date or last period.
Blood Pressure
Classify systolic and diastolic readings into blood pressure categories.
Heart Rate Zones
Training heart rate zones based on your maximum heart rate.
VO2 Max
Estimate maximum oxygen uptake from a timed run or walk test.
Pace Calculator
Running pace, speed, and finish time for any distance.
Calories Burned
Estimate calories burned during physical activities.
Weight Loss
Calorie deficit and timeline to reach your target weight.
Lean Body Mass
Estimate lean body mass from weight and body fat percentage.
Body Fat
Body fat % using the US Navy method.
Ideal Weight
Ideal weight by height and gender.
Dosage
Medication dosage by weight.
Age
Exact age in years, months, and days.
Ovulation
Estimate fertile window.
Lifespan Calculator — CalcxApp
Estimate your statistical life expectancy based on age, exercise habits, and smoking status.
IVF Due Date Calculator - Estimate Your Delivery Date
Calculate your estimated due date from IVF embryo transfer date with visual timeline and progress tracking.
Baby Growth Percentile Calculator - WHO Growth Charts
Track your child growth with WHO-based percentile calculations for weight, height, and head circumference.
Daily Water Intake Calculator - Hydration Needs
Calculate your optimal daily water intake based on weight, activity level, climate, and age.
Medication Dosage Calculator - Weight-Based Dosing
Calculate the correct medication dose based on body weight, dosage per kg, and frequency.
Vitamin D Calculator - Daily Requirement & Supplement Dosage
Calculate your daily Vitamin D requirement based on weight, sun exposure, and current levels.
Hydration Timeline Calculator - Personalized Water Intake S…
Calculate your personalized daily water intake schedule based on weight, activity level, and exercise.
Allergy Season Calendar - Pollen Count by Month
Check pollen levels by month and region to plan your allergy management.
BMI Comparison Calculator - BMI, BMR, TDEE Analysis
Compare your BMI, BMR, and TDEE across different metrics and categories.
RMR Calculator - Resting Metabolic Rate (3 Formulas)
Calculate your RMR using three scientific formulas and compare results.
Glycemic Load Calculator - GL of Foods
Calculate the glycemic load of foods based on carbs, glycemic index, and fiber content.
Cholesterol Ratio Calculator - Cardiovascular Risk Assessme…
Calculate your Total/HDL cholesterol ratio and assess cardiovascular risk.
Kidney Function Calculator (eGFR)
Estimate your glomerular filtration rate (eGFR) using the CKD-EPI formula.
Bone Density Calculator (T-Score Estimator)
Estimate your bone density t-score based on risk factors like age, gender, calcium intake, and exercise.
Visual Acuity Calculator - Snellen Chart Converter
Calculate your visual acuity using Snellen chart measurements and convert between different notation systems.
Hearing Loss Calculator - Audiogram Estimation
Estimate your hearing loss risk based on age, noise exposure, and lifestyle factors with an audiogram visualization.
Sun Exposure Calculator - Safe Tanning Time
Calculate safe sun exposure time based on skin type, UV index, and SPF protection.
Postpartum Calorie Calculator - Breastfeeding Nutrition
Calculate your daily calorie needs during the postpartum period, including breastfeeding requirements.
Pregnancy Calorie Calculator — Trimester Nutrition
Estimate your daily calorie needs during each trimester of pregnancy.
Gestational Age Calculator — Pregnancy Due Date | CalcxApp
Calculate your gestational age, due date, and current trimester based on your last menstrual period.
Waist-to-Hip Ratio Calculator — Health Risk | CalcxApp
Calculate your waist-to-hip ratio to assess body fat distribution and health risk.
Sleep
Recommended sleep duration based on age.
BAC Calculator — Blood Alcohol Content | CalcxApp
Estimate your blood alcohol concentration based on drinks consumed, body weight, and time.
Carb Calculator — Daily Carbs by Goal & Macros | CalcxApp
Free online carb calculator with charts and downloadable results.
Fiber Calculator — Daily Intake by Age & Gender | CalcxApp
Free online fiber calculator with charts and downloadable results.
Cholesterol Ratio Calculator — Heart Health | CalcxApp
Calculate your cholesterol ratios and assess your cardiovascular risk profile.
Stress Level Calculator — Assess Your Stress Online
Assess your stress level by rating five key lifestyle factors
Respiratory Rate Calculator — Normal Breathing Rates by Age
Check if your breathing rate falls within the normal range for your age
Blood Sugar Calculator — Glucose & HbA1c Assessment
Evaluate your blood glucose levels and HbA1c for diabetes risk assessment
Army Body Fat
Body fat % against US Army AR 600-9 standards.
Blood Type Calculator | CalcxApp
Determina posibles tipos de sangre de los padres
Body Surface Area Calculator | CalcxApp
Calcula el área de superficie corporal (BSA)
Calorie Deficit Calculator | CalcxApp
Calcula el déficit calórico para perder peso
Lung Capacity Calculator | CalcxApp
Estima la capacidad pulmonar según altura y edad
Pregnancy Weight Gain Calculator | CalcxApp
Rastrea el aumento de peso recomendado en el embarazo
Sleep Debt Calculator | CalcxApp
Calcula tu deuda de sueño acumulada
Stress Score Calculator | CalcxApp
Evalúa tu nivel de estrés
Waist-to-Height Ratio
Waist-to-height ratio for abdominal obesity.
Heart Rate Zone Calculator | CalcxApp
Calcula las zonas de entrenamiento por frecuencia cardíaca
Water Intake Goal Calculator — CalcxApp
Calculate your optimal daily water intake based on body weight, activity level, and climate. Get a personalized hourly hydration schedule with ml and oz measurements.
Body Fat Percentage Calculator (Navy Method)
Estimate your body fat percentage using the U.S. Navy tape measure method with waist, neck, and height measurements.
Meal Calorie Calculator — Distribute Calories Per Meal
Distribute your daily calorie intake across meals with different strategies for optimal nutrition.
Carb Cycling Calculator — Weekly Macro Plan | CalcxApp
Calculate your weekly macronutrient plan with high, low, and rest day carb targets for cutting, maintaining, or bulking.
Intermittent Fasting Calculator — Fasting Window Schedule
Plan your fasting and eating windows with visual timelines for popular protocols like 16:8, 18:6, 20:4, and OMAD.
Caffeine Calculator — Safe Daily Intake by Weight | CalcxApp
Free online caffeine calculator with charts and downloadable results.
Smoking Cost Calculator — Lifetime Spending | CalcxApp
Free online smoking cost calculator with charts and downloadable results.
Alcohol Cost Calculator — Yearly & Lifetime Spending | CalcxApp
Free online alcohol cost calculator with charts and downloadable results.
Calorie Deficit Calculator — Plan Your Weight Loss
Calculate your daily calorie deficit needed to reach your weight loss goal within your timeline.
Gym Value Calculator — CalcxApp
Calculate the true cost per visit of your gym membership and find out if it's worth it.
Bra Size Converter & Calculator — US, UK, EU | CalcxApp
Find your bra size from measurements with conversions to 7 international sizing systems.
Sister Size Bra Calculator — Find Your Perfect Fit
Find your bra sister sizes — sizes that share the same cup volume with different band sizes. Complete sister size matrix and conversion chart.
Sports Bra Size Calculator — Lululemon, Nike, Shefit
Convert your bra size to S/M/L sports bra sizing for top athletic brands like Lululemon, Nike, Athleta, Shefit, Panache, and Shock Absorber.
Calorie Surplus Calculator — Gain Weight Fast | CalcxApp
Quick and accurate calorie surplus calculator with visual charts and detailed tables.
Weight Loss Calculator — Reach Goal by Date | CalcxApp
Quick and accurate weight loss date calculator with visual charts and detailed tables.
Weight Gain Calculator — Reach Goal by Date | CalcxApp
Quick and accurate weight gain date calculator with visual charts and detailed tables.
Target Heart Rate Calculator — 5 Zones | CalcxApp
Quick and accurate target heart rate calculator with visual charts and detailed tables.
Max Heart Rate Calculator — Karvonen & Tanaka | CalcxApp
Quick and accurate max heart rate calculator with visual charts and detailed tables.
Resting Heart Rate Calculator — Normal Range by Age | CalcxApp
Quick and accurate resting heart rate calculator with visual charts and detailed tables.
Heart Rate Variability (HRV) Calculator | CalcxApp
Quick and accurate heart rate variability calculator with visual charts and detailed tables.
VO2 Max Calculator (Cooper Test) | CalcxApp
Quick and accurate vo2 max cooper test calculator with visual charts and detailed tables.
Rockport Walk Test Calculator — VO2 Max | CalcxApp
Quick and accurate rockport walk test calculator with visual charts and detailed tables.
Youth BMI Calculator — Kids & Teens (CDC) | CalcxApp
Quick and accurate youth bmi calculator with visual charts and detailed tables.
BMI Percentile Calculator — Kids & Teens (CDC) | CalcxApp
Quick and accurate bmi percentile calculator with visual charts and detailed tables.
Adjusted Body Weight Calculator — For Dosing & BMI | CalcxApp
Quick and accurate adjusted body weight calculator with visual charts and detailed tables.
Ideal Body Weight Calculator — IBW | CalcxApp
Quick and accurate ideal body weight calculator with visual charts and detailed tables.
WTHR Calculator — Waist-to-Height Ratio | CalcxApp
Quick and accurate waist-to-height ratio calculator with visual charts and detailed tables.
Waist-to-Hip Ratio Calculator — Health Risk | CalcxApp
Quick and accurate waist-hip ratio calculator with visual charts and detailed tables.
Body Shape Calculator — Hourglass, Pear, Apple | CalcxApp
Quick and accurate body shape calculator with visual charts and detailed tables.
Body Surface Area Calculator — BSA in m² | CalcxApp
Quick and accurate body surface area calculator with visual charts and detailed tables.
BSA Mosteller Calculator — Body Surface Area | CalcxApp
Quick and accurate bsa mosteller calculator with visual charts and detailed tables.
Lean Body Mass Calculator (Boer Formula) | CalcxApp
Quick and accurate boer formula lean mass calculator with visual charts and detailed tables.
RMR Calculator — Resting Metabolic Rate | CalcxApp
Quick and accurate resting metabolic rate calculator with visual charts and detailed tables.
Katch-McArdle BMR Calculator — Lean Body Mass | CalcxApp
Quick and accurate katch mcardle bmr calculator with visual charts and detailed tables.
Harris-Benedict BMR Calculator — Revised 1984 | CalcxApp
Quick and accurate harris-benedict bmr calculator with visual charts and detailed tables.
Cunningham Equation Calculator — 1RM from Reps | CalcxApp
Quick and accurate cunningham equation bmr calculator with visual charts and detailed tables.
One Rep Max Calculator — 1RM from Any Reps | CalcxApp
Quick and accurate one rep max calculator with visual charts and detailed tables.
Bench Press 1RM Calculator — Max from Any Rep | CalcxApp
Quick and accurate bench press 1rm calculator with visual charts and detailed tables.
Epley 1RM Calculator — Max from Any Reps | CalcxApp
Quick and accurate epley 1rm calculator with visual charts and detailed tables.
Brzycki 1RM Calculator — Max from Reps | CalcxApp
Quick and accurate brzycki 1rm calculator with visual charts and detailed tables.
Lombardi 1RM Calculator — Max from Reps | CalcxApp
Quick and accurate lombardi 1rm calculator with visual charts and detailed tables.
O'Conner 1RM Calculator — Max from Reps | CalcxApp
Quick and accurate o'conner 1rm calculator with visual charts and detailed tables.
Wilks Score Calculator — Powerlifting | CalcxApp
Quick and accurate wilks coefficient calculator with visual charts and detailed tables.
DOTS Score Calculator — Strengthlifting | CalcxApp
Quick and accurate dots score calculator with visual charts and detailed tables.
Running Pace Calculator — Min/Mile & Min/Km | CalcxApp
Quick and accurate running pace calculator with visual charts and detailed tables.
Marathon Pace Calculator — Target Finish Time | CalcxApp
Quick and accurate marathon pace calculator with visual charts and detailed tables.
Race Time Predictor — From One Distance to Another | CalcxApp
Quick and accurate race time predictor calculator with visual charts and detailed tables.
5K Time Predictor — Race Time from Any Distance | CalcxApp
Quick and accurate 5k time predictor calculator with visual charts and detailed tables.
Walking Steps Calculator — Distance & Calories | CalcxApp
Quick and accurate walking steps calculator with visual charts and detailed tables.
Steps to Miles Calculator — Convert Pedometer | CalcxApp
Quick and accurate steps to miles calculator with visual charts and detailed tables.
Calories Burned Running Calculator | CalcxApp
Quick and accurate calories burned running calculator with visual charts and detailed tables.
Calories Burned Walking Calculator | CalcxApp
Quick and accurate calories burned walking calculator with visual charts and detailed tables.
Calories Burned Cycling Calculator | CalcxApp
Quick and accurate calories burned cycling calculator with visual charts and detailed tables.
Calories Burned Swimming Calculator | CalcxApp
Quick and accurate calories burned swimming calculator with visual charts and detailed tables.
Calories Burned Yoga Calculator | CalcxApp
Quick and accurate calories burned yoga calculator with visual charts and detailed tables.
Calories Burned HIIT Calculator | CalcxApp
Quick and accurate calories burned hiit calculator with visual charts and detailed tables.
Calories Burned Weight Training Calculator | CalcxApp
Quick and accurate calories burned weight training calculator with visual charts and detailed tables.
Exercise MET Calculator — Calories by Activity | CalcxApp
Quick and accurate met calories calculator with visual charts and detailed tables.
Daily Energy Expenditure Calculator | CalcxApp
Quick and accurate daily energy expenditure calculator with visual charts and detailed tables.
Frequently Asked Questions
Is BMI accurate? ▾
BMI is a population-level screening tool with known limitations for athletes, the elderly, and certain ethnic groups. Use it as a starting point, not a diagnosis. For higher accuracy, pair it with body fat percentage and waist-to-hip ratio.
What is the difference between BMR and TDEE? ▾
BMR is what your body burns at complete rest. TDEE adds your daily activity on top. To lose weight, target 500 calories below TDEE; to maintain, eat at TDEE; to gain, target 250-500 above.
Are these calculators suitable for medical decisions? ▾
No. They are for informational and educational use only. Always consult a qualified healthcare provider for medical decisions, diagnoses, and treatment plans.
Do you store my health data? ▾
No. All calculations run client-side in your browser. No health data is transmitted, stored on our servers, or shared with third parties. We do not require an account.
How often are the formulas updated? ▾
We review formulas quarterly and update them when the underlying clinical guidelines change. The last reviewed date is shown on every page.
Sources & References
The formulas, definitions, and best-practice guidance in these health & fitness calculators are grounded in the following authoritative sources: