Health and fitness calculators
Free body-metric tools—BMI, basal metabolic rate (BMR), daily calories (TDEE), and body fat estimate from circumferences. Use the cards above for instant browser-side math. Not medical advice.
Tools in this category
- BMI calculator — body mass index; metric or US height/weight; adult category bands.
- BMR calculator — Mifflin–St Jeor resting calories (kcal/day).
- Calorie calculator — maintenance calories from activity level; optional daily surplus/deficit.
- Body fat calculator — Navy circumference method (neck, waist, hip for women).
How the tools fit together
BMI is a population screening index. BMR is the resting-energy starting point. Multiply BMR by activity in the calorie tool for weight-maintenance calories. Body fat adds another lens when you have tape measurements and want a percent estimate—not a replacement for clinical testing.
Examples
170 cm and 70 kg → BMI about 24. Same person, male age 30 → BMR near 1650 kcal/day before activity. Moderate activity might land near 2500 kcal TDEE; −500 kcal/day adjustment is a common planning shortcut, not a prescription.
Limitations
Athletes, pregnancy, and some medical conditions make generic formulas less accurate. Body fat from tape measures depends on consistent technique. Always prioritize professional guidance for diet or treatment.
Frequently asked questions
How do I calculate my BMI?
Enter height and weight on the BMI calculator (kg/cm or lb/ft·in). BMI = weight (kg) ÷ height (m)². Example: 170 cm and 70 kg → BMI ≈ 24.2 (normal range for many adults).
What is the difference between BMR and TDEE?
BMR is calories burned at complete rest. TDEE adds daily activity (desk job, workouts, etc.). Use the BMR calculator for resting burn; use the calorie calculator when you need maintenance or weight-loss targets from activity level.
How many calories should I eat per day to lose weight?
Estimate maintenance with the calorie calculator (BMR × activity), then subtract roughly 300–500 kcal/day for a moderate deficit—typical guidance, not personalized medical advice. Very low intakes need professional supervision.
BMI vs body fat percentage—which should I use?
BMI is a quick screen from height and weight only. Body fat estimates fat mass (e.g. Navy circumference method). Athletes may have high BMI with low fat; both numbers are estimates, not diagnosis.
What is a normal BMI for adults?
WHO-style bands often used online: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30+ obese. Ethnicity and muscle mass can shift interpretation—use BMI as a starting point, not a verdict. Child BMI needs growth charts, not these adult bands.
How does the BMR calculator work?
The BMR calculator uses Mifflin–St Jeor: men 10×kg + 6.25×cm − 5×age + 5; women the same with −161 instead of +5. It is a population formula; your lab-measured resting metabolism may differ.
I only know pounds and feet—inches. Which health tools accept US units?
The BMI calculator accepts lb and ft/in directly. BMR, calorie, and body fat forms use cm and kg—convert first with the weight or length converter (e.g. 154 lb ≈ 70 kg, 5 ft 7 in ≈ 170 cm).
What is the Navy body fat calculator?
The body fat calculator applies US Navy circumference equations from waist, neck, and height (hip for women). It is a field estimate—not DEXA or hydrostatic weighing—and works best when measurements are taken consistently.
Can BMI be wrong for muscular or athletic people?
Yes. Muscle weighs more than fat per volume, so lifters and some athletes can land in “overweight” BMI while carrying low body fat. Pair BMI with the body fat tool, waist trend, or clinical assessment if BMI looks off for your build.
Are CalcTool health results medical advice?
No. All pages are educational estimates run locally in your browser—no data uploaded. For eating disorders, pregnancy, chronic disease, or medication changes, rely on a qualified clinician, not an online calculator.