Health Calculators
Evidence-based health and fitness calculators — BMI, BMR, TDEE, macros, body fat and more — with the formulas shown in full.
14 tools, all running in your browser.
Fig 1 Level only at the true weight
Move across to slide the poise · ← →
The beam settles only where the poises balance the load; BMI is that weight over height squared. The health calculators here show their formulas the same way.
Most used
BMI Calculator Work out your body mass index in kg/cm or lb/ft, see the category gauge, your healthy weight range, and what BMI does and does not measure. Calorie Calculator Set a goal weight and a weekly rate, and get your daily calorie target plus a week-by-week timeline showing when you would reach it. Ovulation Calculator Work out your ovulation date and six-day fertile window from your last period and cycle length. Nothing is uploaded and nothing is stored unless you ask. TDEE Calculator Find your maintenance calories from BMR and an honest activity multiplier, with cut, maintain and bulk targets and the full working shown.
Everything else
BMR Calculator Estimate your basal metabolic rate with three published equations side by side, see the working, and learn which one fits your body composition. Body Fat Calculator Estimate body fat percentage from tape measurements with the US Navy formula, cross-check it against the BMI method, and see fat and lean mass. Conception Date Calculator Work backwards from a due date to the estimated conception date and six-day window, or forwards from your last period. Nothing is transmitted. Due Date Calculator Estimate your due date from your last period, conception date, IVF transfer or a dating scan, with gestational age, trimesters and milestones. Ideal Weight Calculator Compare four clinical ideal body weight formulas against the healthy BMI range for your height, in kilograms or pounds, with the maths shown. Macro Calculator Split a calorie target into protein, carbs and fat with balanced, low-carb, high-protein or keto presets, shown in grams, calories and percent. One Rep Max Calculator Estimate your 1RM from any set with the Epley, Brzycki, Lombardi and O’Conner formulas, then read off training weights from 50 to 100 percent. Pace Calculator Convert running pace, speed, time and distance for 5K, 10K, half and full marathon, with a kilometre or mile split table you can copy. Period Calculator Predict your next six periods and premenstrual weeks from one date and your cycle length, with a printable calendar. Private by construction. Water Intake Calculator Estimate daily water needs from body weight, exercise time and climate, in litres, cups or fluid ounces, with the assumptions spelled out.