Health & Fitness
Free health and fitness calculators — body metrics, daily energy needs, and cycle planning — with clear methods and animated visuals.
Body mass index with WHO categories and the healthy weight range for your height.
Daily calorie needs with Mifflin-St Jeor, plus safe targets for losing or gaining weight.
Your resting calorie burn with two research equations and daily burn by activity level.
Body-fat percentage from tape measurements with the US Navy method — no calipers needed.
Your ideal body weight from the four standard formulas plus the healthy BMI range.
Daily protein, carb, and fat gram targets from your TDEE, goal, and preferred split.
How much water to drink per day from your weight, exercise, and climate.
Predict your next three periods, fertile window, and ovulation day on a cycle wheel.
Estimate your due date with Naegele's rule, gestational age today, and trimester milestones.
Every tool here runs a published, named method rather than a proprietary score, and each results page states which one. The body-metric tools form a sequence: the BMI calculator places weight-for-height into the WHO bands (a screening measure — it cannot tell muscle from fat), the body fat calculator refines that with the US Navy circumference method using only a tape measure, and the ideal weight calculator shows the four standard reference formulas side by side so you can see how much they disagree.
The energy tools build on each other in the same way: the BMR calculator estimates resting burn with Mifflin-St Jeor (Harris-Benedict shown for comparison), the calorie calculator multiplies that by an activity level to get TDEE with safe deficit or surplus targets, and the macro calculator splits the result into protein, carb, and fat grams. The period and due date calculators use calendar methods (cycle averaging and Naegele's rule) — useful for planning, but not a contraceptive method and not a substitute for an ultrasound date.
All results are general education, not medical advice. Formulas fitted to population averages can be off for any individual — athletes, older adults, and people with medical conditions especially — so confirm decisions that affect your health with a professional.