Health & Fitness calculators
BMI, calorie, body fat, heart rate, pregnancy and running calculators based on published clinical formulas.
BMI Calculator
Calculate your body mass index in metric or US units, see your weight category and the healthy weight range for your height.
Calorie Calculator
Find your daily calorie needs (TDEE) to maintain, lose or gain weight, based on age, sex, size and activity level.
Ovulation Calculator
Estimate your ovulation date and fertile window for the next six cycles from your last period and cycle length.
Pregnancy Due Date Calculator
Estimate your baby's due date, conception date and how many weeks pregnant you are from the first day of your last period.
BMR Calculator
Estimate your basal metabolic rate, the calories your body burns at complete rest, with the Mifflin-St Jeor and Harris-Benedict equations.
Body Fat Calculator
Estimate your body fat percentage from a few tape measurements using the US Navy circumference method.
Calories Burned Calculator
Estimate calories burned during walking, running, cycling, swimming, lifting and other activities based on your weight.
Heart Rate Zone Calculator
Find your maximum heart rate and five training zones, with the Karvonen method if you know your resting heart rate.
Ideal Weight Calculator
Estimate your ideal body weight with four classic formulas (Robinson, Miller, Devine, Hamwi) and the healthy BMI range.
Macro Calculator
Split your daily calories into grams of protein, carbohydrates and fat for balanced, low-carb, high-protein or keto diets.
One Rep Max Calculator
Estimate your one-rep max from a set of several reps, with training loads for every percentage of 1RM.
Protein Intake Calculator
Calculate how many grams of protein you need per day for health, exercise, muscle gain or fat loss.
Running Pace Calculator
Calculate running pace per kilometer and per mile, speed, and projected 5K, 10K, half and full marathon times.
Sleep Calculator
Find the best times to go to bed or wake up so you finish a full 90-minute sleep cycle and wake feeling rested.
Water Intake Calculator
Estimate how much water you should drink each day based on body weight, exercise and climate.
About the health calculators
These tools use formulas from peer-reviewed research and public-health guidance, such as the Mifflin-St Jeor equation for metabolic rate and the U.S. Navy method for body fat. Each page names the formula it uses so you can look it up.
Population formulas describe averages. Your own body can differ by 10% or more, so treat results as a starting point and talk to a doctor or registered dietitian before making big changes, especially if you are pregnant or have a medical condition.
Health & Fitness guides
Your Fertile Window Explained: How to Pinpoint OvulationWhy ovulation is counted back from your next period, how long the fertile window lasts, and which tracking methods are most accurate.
How Much Protein Do You Need Per Day?The official minimum is lower than most active people need. Here is how much protein to eat for health, muscle gain and fat loss, with food examples.
How Many Calories Should You Eat to Lose Weight?A step-by-step method to find your calorie target, why the 3,500-calorie rule is only approximate, and how to adjust when progress stalls.
BMI vs Body Fat Percentage: Which Number Should You Track?BMI is quick and useful for populations, but it cannot tell muscle from fat. Here is what each measure tells you and how to combine them with your waist size.