Fitness & Health
Understand your body with 28 free health and fitness calculators. Each one uses a validated, published formula, such as Mifflin–St Jeor for BMR, CKD-EPI 2021 for eGFR, Karvonen for heart-rate zones and Naegele’s rule for due dates, and cites the original research.
Calculate Body Mass Index for adults.
Estimate daily calorie needs based on activity level.
Open calculatorEstimate body fat percentage using measurements.
Open calculatorCalculate Basal Metabolic Rate (calories at rest).
Open calculatorFind ideal body weight ranges for your height.
Calculate running pace, distance, or time.
Open calculatorU.S. Army body fat percentage estimation.
Calculate lean body mass from total weight and body fat.
Open calculatorFind the healthy weight range for your height.
Open calculatorEstimate calories burned during various activities.
Estimate your one-repetition maximum for strength exercises.
Open calculatorFind your target heart rate zones for exercise.
Open calculatorTrack pregnancy weeks, trimester, and due date.
Open calculatorRecommended weight gain during pregnancy by BMI.
Calculate estimated due date from last menstrual period.
Open calculatorEstimate conception date from due date or LMP.
Predict next period and cycle dates.
Open calculatorFind fertile window and likely conception dates.
Open calculatorPredict ovulation and fertile days.
Calculate daily macronutrient targets.
Open calculatorFind daily carbohydrate intake recommendations.
Open calculatorEstimate daily protein needs based on weight and goals.
Open calculatorCalculate recommended daily fat intake.
Estimate Glomerular Filtration Rate for kidney health.
Open calculatorCalculate Total Daily Energy Expenditure.
Determine your somatotype (ectomorph, mesomorph, endomorph).
Open calculatorCalculate body surface area for medical dosing.
Open calculatorAverage Handle Time calculator for call centers.
Which fitness & health calculator do I need?
Our 28 tools grouped by the job they do. Pick the group that matches your question.
Body weight & composition
Check where your weight sits on the BMI scale, estimate body-fat percentage from tape measurements, and find a healthy weight range for your height.
Calories, metabolism & nutrition
Find how many calories you burn at rest (BMR) and in a full day (TDEE). Then set calorie, protein, carb and fat targets for losing, maintaining or gaining weight.
Training & performance
Train at the right intensity with heart-rate zones, plan race splits with the pace calculator, and estimate your one-rep max for strength programming.
Pregnancy, fertility & cycle tracking
Estimate your due date, see which week of pregnancy you are in, find your fertile window and predict your next period.
Clinical & workplace
Estimate kidney function (eGFR) from a serum creatinine result, and measure contact-centre average handle time.
Fitness & Health: frequently asked questions
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) is the energy your body burns at complete rest. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor, so it covers everything you burn in a day. Eat below your TDEE to lose weight and above it to gain.
How do I calculate my target heart rate?
The Karvonen formula is: target HR = ((max HR − resting HR) × intensity) + resting HR. Max HR is roughly 220 − age, or 208 − 0.7 × age using the Tanaka equation. Moderate exercise is about 50–70% intensity and vigorous exercise about 70–85%.
Which eGFR formula do you use?
The GFR Calculator uses the race-free CKD-EPI 2021 creatinine equation, which the National Kidney Foundation and the American Society of Nephrology recommend for adults in the United States.
Is BMI accurate?
BMI is a fast screening measure, but it cannot tell muscle from fat. Very muscular people can show as overweight. For a fuller picture, pair BMI with the Body Fat or Lean Body Mass calculators.
Can these calculators replace medical advice?
No. They give estimates based on population formulas. Always talk to a doctor, midwife or registered dietitian before making health decisions, especially during pregnancy or if you have a medical condition.