health Calculators
Last updated: May 2026
BMI Calculator
Body Mass Index (BMI) is the most widely used screening tool for relating a person's weight to their height.
Calories Burned Calculator
Estimate calories burned during exercise from body weight, activity intensity (METs), and duration.
Daily Water Intake Calculator
Estimate how much water you should drink each day based on body weight and activity level — a far better starting point than the generic "8 glasses a day" rule, which has no scientific basis.
Heart Rate Zone Calculator
Calculate your personalised heart rate training zones using the Karvonen heart rate reserve method, which factors in resting heart rate to give zones that actually reflect your cardiovascular fitness.
Body Fat Percentage Calculator
Estimate your body fat percentage from a tape measure using the US Navy circumference method — the same protocol the US military uses for fitness compliance.
Blood Pressure Category Calculator
Classify blood pressure readings into clinical categories (normal, elevated, Stage 1 hypertension, Stage 2 hypertension) based on systolic and diastolic values.
Pregnancy Due Date Calculator
Estimate your due date and current pregnancy week from how many days ago your last menstrual period started, your average cycle length, and the dating method.
Ideal Weight Calculator
Estimate your "ideal" reference body weight from your height, biological sex, and body frame size using the Devine formula — originally created in 1974 for pharmacological dose calculation and still used clinically today.
Sleep Schedule Calculator
Find a bedtime that lets you wake up at the end of a complete 90-minute sleep cycle, minimising the groggy, disoriented feeling (sleep inertia) of being yanked out of deep sleep by an alarm.
Daily Protein Calculator
Calculate daily protein intake target in grams based on your body weight, activity level multiplier, and goal multiplier.
BMR & Daily Calorie Needs Calculator
Calculate Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, then multiply by an activity factor to estimate Total Daily Energy Expenditure (TDEE) — the calories you burn in a typical day.
Macro Split Calculator
Break down your daily calorie target into grams of protein, carbohydrates, and fat based on your chosen macro percentages.
BMI & Body Fat Percentage Calculator
Calculate your BMI and estimate body fat percentage from body measurements using the U.S.
Calorie Deficit & Weight Loss Calculator
Estimate how much weight you'll lose over a set number of weeks from your daily calorie deficit and exercise.
Daily Water Intake Calculator
Estimate your daily water needs from body weight, activity level, climate, and health factors.
Sleep Cycle & Wake Time Calculator
Work backward from your desired wake time to find the ideal bedtime based on your age and sleep quality factors.
Blood Pressure Risk Assessment Calculator
Estimate your cardiovascular risk score from systolic and diastolic blood pressure, age, gender, and lifestyle risk factors.
BMR & TDEE Calculator
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the Mifflin–St Jeor equation.
Body Fat Percentage Calculator
Estimate your body fat percentage using the US Navy tape-measure method.
Macro Calculator
Split your daily calorie target into grams of protein, carbohydrates, and fat tuned to your goal — fat loss, muscle gain, maintenance, or keto.
Blood Pressure Category Calculator
Calculate your mean arterial pressure (MAP) from your systolic and diastolic readings.
Pregnancy Due Date Calculator
Estimates your due date, current pregnancy week, and trimester from your last menstrual period or conception date.
BMR / TDEE Calculator
Estimate your daily calorie needs using the revised Harris-Benedict equation, then adjust for activity to get your Total Daily Energy Expenditure (TDEE) — the rough number of calories you burn in 24 hours when you eat a maintenance diet.
Body Surface Area Calculator
Calculate your Body Surface Area (BSA) in m² using the Mosteller, Haycock, or DuBois formula.
Blood Pressure Category Calculator
Classifies your blood pressure reading into standard AHA categories — from Normal to Hypertensive Crisis — and estimates your overall cardiovascular risk score by factoring in age and additional risk factors.
Heart Rate Training Zones Calculator
Finds your target heart rate for each training zone using either the simple percentage-of-max method or the more precise Karvonen formula.
Pregnancy Due Date & Week Calculator
Calculates your estimated due date, current pregnancy week, and trimester from your last menstrual period or conception date.
Ideal Weight Calculator
Estimates your ideal body weight in kilograms using four established clinical formulas — Hamwi, Devine, Robinson, and Miller — based on height and gender.
Blood Alcohol Content (BAC) Calculator
Estimates your blood alcohol content (BAC) as a percentage and predicts when you will reach zero based on drinks consumed, body weight, gender, and time elapsed.
Lean Body Mass Calculator
Estimate your lean body mass — everything except fat — from height, weight, and sex using the Boer formula.
Waist-to-Hip Ratio Calculator
Divides your waist circumference by your hip circumference to gauge how body fat is distributed — a strong, simple predictor of cardiometabolic risk.
Body Fat Calculator (Navy Method)
Estimates body fat percentage using the U.S.