Health and Fitness Calculators
These calculators apply well-known published formulas to the numbers you enter. They are useful for getting a rough baseline and for tracking change over time, and they are not a substitute for a clinical assessment.
Health & Fitness Calculators (13)
Guides for This Topic
What BMI Can and Cannot Tell You
BMI compares weight to height and nothing else. It does not distinguish muscle from fat, so it misclassifies athletes as overweight and can miss low muscle mass in older adults. It was designed to describe populations, not individuals. As a single data point tracked over time it has some value; as a verdict on one person's health it has very little.
Calorie Estimates Are Starting Points
Formulas such as Mifflin-St Jeor estimate resting energy expenditure, then multiply by an activity factor that you choose yourself. That activity factor is the largest source of error, and most people overestimate it. Treat the output as a starting figure to test over two or three weeks, adjusting based on what actually happens rather than on what the formula predicted.
Cycle and Pregnancy Dates Are Averages
Ovulation and due date calculations assume a regular cycle of a standard length. Real cycles vary between people and from month to month. These estimates are useful for planning and for knowing roughly what to expect, but they are not diagnostic and should not be relied on as contraception or as a substitute for medical confirmation.
When to Ask a Professional Instead
If a result surprises you, if you are managing a medical condition, if you are pregnant, or if you are making a significant change to diet or training, talk to a doctor or a qualified practitioner. A calculator does not know your history, your medication, or your bloodwork, and those are exactly the things that change the answer.