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Health & Fitness Calculators

Free Health & Fitness Calculators

30+ free health calculators based on CDC, WHO, and peer-reviewed formulas. Calculate your BMI, daily calorie needs, TDEE, pregnancy due date, body fat percentage, ideal weight, macros, and more — no sign-up, no ads.

30+ Free Calculators CDC & WHO Verified Formulas Updated 2025 No Sign-Up Required
Quick BMI Calculator
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Your BMI
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Medical Disclaimer: These calculators are for informational and educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or a qualified healthcare provider with questions about your health.

The tools millions of Americans use every month for fitness and wellness

🔥 Most Popular CDC Formula

BMI Calculator

Calculate your Body Mass Index using height and weight. Supports both Imperial (lbs/inches) and Metric (kg/cm) units. Results include BMI category — Underweight, Normal, Overweight, or Obese — based on official CDC and WHO adult BMI classifications.

Adult BMI (18+) Imperial & Metric BMI category Healthy weight range CDC classification
what is a healthy BMI BMI chart for women BMI calculator by age overweight BMI range
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Calorie Calculator

Find out exactly how many calories you should eat per day based on age, sex, height, weight, and activity level. Includes goals for weight loss, maintenance, and muscle gain.

Daily calorie needs Weight loss goal Muscle gain
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Trending Fitness

TDEE Calculator – Total Daily Energy Expenditure

Calculate your Total Daily Energy Expenditure — the number of calories your body burns in a day including exercise. The most precise starting point for any diet or fitness goal. Uses the Mifflin-St Jeor equation (most accurate BMR formula) with 5 activity multipliers.

Maintenance calories Cutting & bulking Mifflin-St Jeor BMR 5 activity levels Calorie deficit/surplus
how many calories do I burn a day TDEE for weight loss maintenance calories calculator
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For Women

Pregnancy Due Date Calculator

Calculate your estimated due date using your last menstrual period (LMP) or conception date. Shows current week of pregnancy and trimester.

Due date (LMP) Weeks pregnant Trimester tracker
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Fitness

Body Fat Calculator

Estimate your body fat percentage using the U.S. Navy method (neck, waist, hip measurements). Includes ACE body fat category reference.

Navy tape method Fat mass (lbs) Lean mass (lbs)
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Fitness Popular

Macro Calculator – Protein, Carbs & Fat

Calculate your ideal daily macronutrient intake (protein, carbohydrates, and fat) based on your TDEE and goal. Supports presets for weight loss, muscle gain, keto, and maintenance. Outputs grams per macro and calorie breakdown.

Protein in grams Carbs & fat targets Keto preset Cutting & bulking Custom % split
how much protein per day macro calculator for weight loss keto macros calculator
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Popular

Ideal Weight Calculator

Find your ideal weight range by height and sex using the Hamwi, Devine, Robinson, and Miller formulas. Includes BMI-based healthy weight range.

4 proven formulas By height & sex Weight goal setting
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Popular

BMR Calculator

Calculate your Basal Metabolic Rate — the calories your body burns at complete rest. Uses both Mifflin-St Jeor and Harris-Benedict equations for comparison.

Mifflin-St Jeor Harris-Benedict At-rest calories
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For Women High Volume

Period Calculator & Cycle Tracker

Predict your next period date and track your menstrual cycle. Enter the date of your last period and your average cycle length to see your next 6 predicted periods, fertile window, and ovulation date.

Next period date 6-month forecast Fertile window Ovulation date Custom cycle length
when is my next period period tracker calculator ovulation calculator
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BMI Categories — CDC Reference

Official Body Mass Index classification for adults (age 20+)

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Below 18.5 18.5 25.0 30.0 40+
Underweight
BMI < 18.5
Normal Weight
18.5 – 24.9
Overweight
25.0 – 29.9
Obese (Class I–III)
BMI ≥ 30.0

Source: Centers for Disease Control and Prevention (CDC). BMI is a screening tool, not a diagnostic tool. Consult your healthcare provider for interpretation.

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Health Calculators
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All Health & Fitness Calculators

Browse the complete list of free health tools

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BMI Calculator
Body Mass Index, CDC categories, healthy weight range
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Calorie Calculator
Daily calories by goal — lose, maintain, or gain weight
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TDEE Calculator
Total daily energy expenditure, activity multipliers
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BMR Calculator
Basal metabolic rate — Mifflin-St Jeor & Harris-Benedict
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Macro Calculator
Protein, carbs & fat targets by goal (keto, cut, bulk)
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Protein Calculator
Daily protein target by body weight and activity level
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Calorie Deficit Calculator
Deficit for weight loss, lbs lost per week projection
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Ideal Weight Calculator
Hamwi, Devine, Robinson, Miller formulas by height
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Body Fat Calculator
U.S. Navy tape method — fat mass & lean mass in lbs
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Water Intake Calculator
Daily hydration needs in oz and liters by weight & activity
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Pregnancy Due Date Calculator
Due date from LMP or conception date, weeks pregnant
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Period & Cycle Calculator
Next period, fertile window, 6-month forecast
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Ovulation Calculator
Ovulation date, fertile days, conception window
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One Rep Max Calculator (1RM)
Max strength estimate — Epley, Brzycki, Lander formulas
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Running Pace Calculator
Pace, speed, finish time — 5K, 10K, half, marathon
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Heart Rate Zone Calculator
Max HR, fat burn zone, cardio zone by age
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Sleep Calculator
Best bedtime by wake time, 90-min sleep cycle
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Weight Loss Calculator
Time to reach goal weight, weekly loss rate, date
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BMI Calculator for Children
CDC BMI-for-age percentile chart (ages 2–19)
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VO2 Max Calculator
Aerobic fitness estimate from resting heart rate
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Health Reference Tables

Quick-reference values from CDC, WHO, and AHA guidelines

HeightUnderweight (<18.5)Normal (18.5–24.9)Overweight (25–29.9)Obese (≥30)
5'0" (152 cm)< 95 lbs95–128 lbs128–153 lbs≥ 153 lbs
5'4" (163 cm)< 108 lbs108–145 lbs145–174 lbs≥ 174 lbs
5'6" (168 cm)< 115 lbs115–154 lbs154–185 lbs≥ 185 lbs
5'9" (175 cm)< 125 lbs125–168 lbs168–202 lbs≥ 202 lbs
5'11" (180 cm)< 133 lbs133–178 lbs178–214 lbs≥ 214 lbs
6'0" (183 cm)< 136 lbs136–183 lbs183–221 lbs≥ 221 lbs
6'2" (188 cm)< 144 lbs144–194 lbs194–233 lbs≥ 233 lbs

→ Calculate your exact BMI · Source: CDC Adult BMI Guidelines

Age RangeMen (Moderately Active)Women (Moderately Active)Men (Sedentary)Women (Sedentary)
19–25 years2,800 cal2,200 cal2,600 cal2,000 cal
26–30 years2,600 cal2,000 cal2,400 cal1,800 cal
31–50 years2,600 cal2,000 cal2,200 cal1,800 cal
51–60 years2,400 cal1,800 cal2,200 cal1,600 cal
61–70 years2,400 cal1,800 cal2,000 cal1,600 cal
71+ years2,200 cal1,600 cal2,000 cal1,600 cal

→ Get your personalized calorie target · Source: USDA Dietary Guidelines 2020–2025

AgeMax HR (BPM)Fat Burn Zone (50–70%)Cardio Zone (70–85%)Peak Zone (85–100%)
20 years200 BPM100–140 BPM140–170 BPM170–200 BPM
25 years195 BPM98–137 BPM137–166 BPM166–195 BPM
30 years190 BPM95–133 BPM133–162 BPM162–190 BPM
35 years185 BPM93–130 BPM130–157 BPM157–185 BPM
40 years180 BPM90–126 BPM126–153 BPM153–180 BPM
50 years170 BPM85–119 BPM119–145 BPM145–170 BPM
60 years160 BPM80–112 BPM112–136 BPM136–160 BPM

→ Calculate your heart rate zones · Source: American Heart Association

Goalg per kg bodyweightg per lb bodyweightExample: 150 lbs (68 kg)Reference
Sedentary (minimum)0.8 g/kg0.36 g/lb54 g/dayRDA / WHO
Weight loss (preserve muscle)1.2–1.6 g/kg0.54–0.73 g/lb82–109 g/dayISSN 2017
Endurance athletes1.4–1.6 g/kg0.64–0.73 g/lb95–109 g/dayACSM / ADA
Muscle building1.6–2.2 g/kg0.73–1.0 g/lb109–150 g/dayMorton et al. 2018
Strength athletes (maximum)2.2–3.1 g/kg1.0–1.4 g/lb150–213 g/dayHelms et al. 2014

→ Calculate your protein target

Find the Right Health Calculator for Your Goal

Whether you're trying to lose weight, build muscle, track your pregnancy, run a faster 5K, or simply understand your body better — our free health calculators have you covered.

Weight & Body Composition

What is a healthy BMI for my height? What is my ideal weight by height? How to calculate body fat percentage How much calorie deficit to lose 1 lb per week How long to lose 20 pounds? BMI calculator for women BMI calculator for men

Nutrition & Calories

How many calories should I eat per day? How many calories do I burn a day? What are my macros for weight loss? How much protein should I eat to build muscle? How much water should I drink per day? Keto macro calculator Calorie calculator during pregnancy

Fitness & Women's Health

How to calculate one rep max (1RM) Marathon pace calculator Target heart rate for fat burning When is my due date? When is my next period? When do I ovulate? What time should I go to sleep?

Health Calculator FAQs

Expert answers based on CDC, WHO, and peer-reviewed research

What is a healthy BMI range for adults?
According to the CDC and WHO, a healthy BMI for adults is 18.5 to 24.9. Below 18.5 is underweight; 25.0–29.9 is overweight; 30+ is obese. BMI doesn't account for muscle mass or fat distribution. Use our BMI calculator for your result, and consider body fat percentage for a fuller picture.
How many calories should I eat to lose weight?
A 500-calorie daily deficit leads to roughly 1 lb of fat loss per week. Start with your TDEE and subtract 300–500 calories. Most experts recommend not going below 1,200 cal/day for women or 1,500 cal/day for men without medical supervision. Use our calorie calculator to find your target.
How is pregnancy due date calculated?
The standard method is Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). This assumes a regular 28-day cycle. Only ~5% of babies are born on their exact due date. Our pregnancy calculator also shows your current week and trimester.
What is TDEE and how is it different from BMR?
BMR (Basal Metabolic Rate) is the calories burned at complete rest. TDEE (Total Daily Energy Expenditure) = BMR × activity multiplier. TDEE is always higher than BMR and represents your true total calorie burn including daily movement and exercise. Set calorie goals based on TDEE, not BMR. Use our TDEE calculator for your number.
How do I calculate body fat percentage?
The most accessible home method is the U.S. Navy tape method, using neck, waist (and hips for women) measurements. Healthy ranges: Men: 6–17% (fit), 18–24% (acceptable) · Women: 14–20% (fit), 21–31% (acceptable) — per ACE guidelines. Use our body fat calculator with just a tape measure.
How much protein should I eat per day?
The RDA is 0.8g/kg for sedentary adults. For muscle building, research supports 1.6–2.2g/kg. For weight loss while preserving muscle, aim for 1.2–1.6g/kg. A 150 lb (68 kg) person building muscle needs ~109–150g protein/day. Use our protein calculator for your exact target.
What is a healthy resting heart rate?
The American Heart Association defines a normal adult resting heart rate as 60–100 BPM. Athletes may be 40–60 BPM. Your maximum heart rate ≈ 220 minus your age. For fat burning, exercise at 50–70% of max HR; for cardiovascular fitness, 70–85%. Use our heart rate zone calculator.
How many calories does a 1 lb of fat equal?
One pound of body fat contains approximately 3,500 calories. To lose 1 lb/week, maintain a deficit of 500 cal/day (500 × 7 = 3,500). To lose 2 lbs/week, maintain a 1,000 cal/day deficit. This is a well-established estimate; actual results vary by individual metabolism, diet composition, and activity.

How We Build Our Health Calculators

Every health calculator on this site is built using formulas validated by the Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO), the American Heart Association (AHA), and peer-reviewed exercise science literature.

Our BMI calculator uses the CDC's standard formula (weight in lbs × 703 ÷ height in inches²) and applies the WHO adult BMI classification thresholds. Our TDEE calculator uses the Mifflin-St Jeor equation (validated as the most accurate BMR prediction model for the general population) with the standard PAL (Physical Activity Level) multipliers.

Calorie and macro recommendations are based on the USDA Dietary Guidelines for Americans 2020–2025 and the International Society of Sports Nutrition (ISSN) position stands. Pregnancy calculations use Naegele's Rule, the standard clinical method used by OB/GYN physicians across the United States.

Medical Disclaimer: These tools are for informational purposes only and do not constitute medical advice. Individual results vary. Always consult a licensed physician, registered dietitian, or certified fitness professional before making changes to your diet, exercise, or health regimen.