Calm, source-linked explanations of the numbers behind common health calculators, and what those numbers can and cannot tell you.
Health calculators turn a few measurements into a useful starting estimate: a BMI category, a daily calorie figure, a rough water target or a body fat percentage. They use published formulas, so they are consistent and quick. They are also simplifications. None of them knows your medical history, medication, pregnancy, training or how your body differs from the averages the formulas were built on.
Treat a result as a starting point and watch the trend over weeks rather than reacting to one reading. Measure the same way each time, for example in the morning and with the same scale or tape. If a number worries you, or you have a health condition, please get personal advice from a qualified professional. Nothing on this site is medical advice.
Health & Fitness · · 5 min read
What official guidelines say about daily water intake, why the 8-glasses rule is only a rough guide, and how body weight, exercise and heat change your needs.
Health & Fitness · · 5 min read
Estimate how many calories you need to lose weight safely: work out maintenance calories (TDEE), choose a moderate deficit and adjust using real results.
Health & Fitness · · 5 min read
Measure your body fat percentage at home with a tape measure and the U.S. Navy method: where to measure, worked examples, accuracy and other methods compared.
Health & Fitness · · 2 min read
Understand basal metabolic rate, total daily energy expenditure, activity multipliers and how to set a realistic calorie target.
Health & Fitness · · 2 min read
How body mass index is calculated, what the categories mean, where BMI falls short, and better measures to use alongside it.
