Pick a calculator
Every tool below runs instantly and privately in your browser — nothing you type is uploaded anywhere.
BMI Calculator
Body Mass Index from your height and weight, with the standard WHO category.
BMI doesn't distinguish muscle from fat — use alongside body fat % for a fuller picture.
Calorie Calculator (TDEE)
Daily calorie needs using the Mifflin-St Jeor equation and your activity level.
Body Fat % Calculator
U.S. Navy circumference method — just a tape measure needed.
Ideal Weight Calculator
Reference range using the Devine formula, standard in clinical dosing.
Water Intake Calculator
Daily hydration target based on body weight and activity.
Heart Rate Zone Calculator
Training zones from your max heart rate, optionally using heart-rate reserve.
Pregnancy Due Date Calculator
Estimated due date from your last menstrual period (Naegele's rule).
An estimate only — about 5% of babies arrive on their exact due date. Confirm with a care provider.
Guides worth reading
Short, practical explainers behind the numbers.
Why BMI Doesn't Tell the Whole Story
What BMI actually measures, where it breaks down, and what to check alongside it.
TDEE Explained: Turning a Number Into a Plan
How to move from a maintenance-calorie estimate to a realistic weekly target.