Free Health Calculators — BMI, Calories, Due Date & More
Calculate your BMI using WHO standards, find your daily calorie and macro targets, estimate your pregnancy due date and milestones, and compute exact date differences — free health tools that keep your personal data private.
All Health Tools
Calorie & Macro Calculator
Calculate daily calorie needs and macronutrient ratios.
HealthPregnancy Due Date Calculator
Calculate your pregnancy due date and week-by-week milestones.
HealthBody Fat Calculator
Calculate body fat percentage using the US Navy method.
HealthSleep Cycle Calculator
Find the best bedtime or wake-up time based on sleep cycles.
HealthWater Intake Calculator
Calculate your recommended daily water intake.
HealthOvulation Calculator
Find your fertile window and estimated ovulation date.
HealthIdeal Weight Calculator
Calculate your ideal body weight using 5 different medical formulas.
HealthMacro Calculator
Calculate your daily protein, carbs, and fat targets based on your goals.
HealthHeart Rate Zone Calculator
Calculate your 5 heart rate training zones based on your max heart rate.
HealthAbout Health Tools
Health calculations are personal, and personal data should stay on your device. Every tool in this health category runs entirely in your browser — your weight, height, age, and other health inputs are never sent to any server or stored in any database.
The BMI Calculator uses the standard WHO Body Mass Index formula (weight in kg divided by height in metres squared) and provides your BMI value alongside the corresponding weight classification: Underweight, Normal weight, Overweight, or Obese. It supports both metric and imperial inputs.
The Calorie & Macro Calculator computes your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor formula — the most widely recommended BMR equation in current nutrition science. It then adjusts for your activity level and goal (lose weight, maintain, or gain muscle) to produce personalised calorie and macronutrient targets.
The Pregnancy Due Date Calculator lets you enter your last menstrual period (LMP) or known conception date to estimate your due date, current gestational week, and trimester, plus key developmental milestones. The Date Difference Calculator rounds out the category, computing exact intervals between any two dates in years, months, weeks, and days.
These tools are intended as a helpful reference and should not replace professional medical advice. Always consult a qualified healthcare provider for medical decisions.
Frequently Asked Questions
How is BMI calculated?
BMI is calculated as weight (kg) divided by height (m) squared. For imperial inputs, the formula is weight (lb) × 703 divided by height (in) squared. WHO classifications range from Underweight (<18.5) to Obese (≥30).
Are these health tools medically accurate?
The tools use standard, widely-accepted medical formulas (WHO BMI classifications, Mifflin-St Jeor for TDEE, Naegele's rule for due dates). However, they are for reference only and do not replace professional medical advice.
Is my health data private?
Yes. All inputs — including your weight, height, age, and health goals — are processed exclusively in your browser and are never sent to any server or stored in any database.
Which BMR formula is used in the Calorie Calculator?
The Calorie Calculator uses the Mifflin-St Jeor equation, which is currently recommended by the Academy of Nutrition and Dietetics as the most accurate BMR formula for the general population.
What is the calorie target based on?
The calorie target is your BMR multiplied by an activity factor (sedentary to very active), then adjusted by ±250–500 calories depending on your goal: lose weight, maintain weight, or build muscle.