Health calculators

Health calculators turn measurements you already have — height, weight, a waist or neck circumference, a resting heart rate, a blood pressure reading — into numbers you can compare over time. One cluster handles body measures: the BMI Calculator converts weight and height into a screening category, while the Legacy Circumference Body Fat Estimate applies a coefficient set to circumference entries to estimate fat and lean mass. A second cluster covers energy and nutrition, like the BMR Calculator, which estimates resting calories with the Mifflin-St Jeor and Harris-Benedict equations, and the Resting Energy Expenditure Calculator, which returns a single predicted kcal-per-day figure without adding activity multipliers or intake targets. Others in the family estimate training loads, heart-rate zones, pregnancy dates, and clinical screening scores.

Choosing the right tool comes down to what you know and what you want back. If you have height and weight, a body-measure tool like BMI gives a fast, reproducible reference. If your goal is nutrition planning, start with an energy estimate such as BMR or resting energy expenditure, then combine it with activity and macro tools rather than treating a single resting figure as your calorie budget. For training, pick a tool built on workout data — a lifted weight or an age-derived heart-rate range. For screening, the calculators are only useful when you actually have the clinical measure, such as a blood pressure reading or a lab value, because they interpret inputs rather than generate them.

Every result here comes from population-level equations, which means it describes typical people, not you specifically. Muscle mass, age, ethnicity, pregnancy, medications, and measurement technique all shift real-world values, so treat each output as a starting point for a conversation, not a verdict. Track the trend — repeated readings over weeks — rather than reacting to any single number, and keep the same measurement method each time so changes reflect reality, not technique.

Finally, the honest limit: these are informational estimates, not medical assessments. Screening categories and scores do not diagnose conditions, and no formula here replaces a clinician’s judgment or qualified care. If you have symptoms, an abnormal reading, or decisions about treatment, diet, or training that matter to your health, take the numbers to a healthcare professional rather than acting on them alone.