Health & nutrition calculators.
Understand general estimates and their limitations.
Nutrition Calculator
Estimate daily calorie needs and protein, fat and carbohydrate grams using your measurements and activity level.
BMI Calculator
Calculate adult body mass index from height and weight in metric or imperial units, with category context.
Ideal Weight Calculator
Reference body weight for a height using the Devine formula, in centimetres or inches, kg and pounds.
Pregnancy Due Date Calculator
Estimate a pregnancy due date and gestational age from the last menstrual period and average cycle length.
Ovulation Calculator
Estimate ovulation and fertile-window dates from the first day of a period and the average cycle length.
Water Intake Calculator
Estimate daily water intake from body weight and activity, in litres and glasses or ounces and cups.
Body Fat Percentage Calculator
Estimate body fat percentage from tape measurements using the US Navy method, in centimetres or inches.
Waist-to-Hip Ratio Calculator
Work out waist-to-hip ratio in centimetres or inches and compare it against the WHO screening thresholds.
Heart Rate Zone Calculator
Calculate five training heart rate zones in beats per minute from an age-predicted maximum heart rate.
BMR / Resting Energy Calculator
Estimate adult resting energy using the Mifflin–St Jeor equation.
Macro (Protein/Carb/Fat) Calculator
Split a daily calorie target into protein, fat, and carbohydrate grams.
Sleep Cycle Calculator
Work out bedtimes or wake-up times based on 90-minute sleep cycles.
Calories Burned Calculator
Estimate calories burned for common activities using MET values.
About health & nutrition calculators
General estimates for body measurements and daily energy: BMI, body fat percentage, waist-to-hip ratio, ideal weight range, resting and daily energy needs, macronutrient splits, water intake, heart rate training zones, sleep cycles, and dates in a pregnancy or ovulation cycle.
These are screening references and population-level formulas, not diagnosis, treatment, or a personal plan. They were derived from studies of general adult populations and will fit some people poorly — athletes, older adults, pregnant people and children in particular. A result outside a usual range is a reason to speak to a clinician, not a conclusion in itself. Every tool states the formula it uses and where it stops being reliable.