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Health and Fitness Calculators

Each of these calculators implements a specific published equation — Mifflin-St Jeor for metabolic rate, the US Navy circumference method for body fat, the Devine formula for reference weight, Naegele's rule for a due date — and each of those equations was derived from a particular population under particular assumptions.

That matters more than the arithmetic. These figures are estimates with real error margins, and they are not a medical assessment. They are useful for tracking a trend over time, and unreliable as a single verdict about one person.

Tools in Health and Fitness Calculators

BMI Calculator

Calculate your Body Mass Index (BMI).

Calorie Calculator

Turn a basal metabolic rate into a daily calorie target.

Body Fat Calculator

Estimate body fat percentage.

BMR Calculator

Calculate Basal Metabolic Rate.

Macro Calculator

Determine optimal macronutrient ratios.

Ideal Weight

Find your ideal weight range.

Pregnancy Calculator

Track pregnancy progress.

Pregnancy Weight Gain

Estimate healthy weight gain.

How these tools behave

  • Inputs and results use metric units: kilograms and centimetres.
  • Nothing entered here is stored or transmitted; the values exist only in the page.
  • These calculators do not diagnose anything and are not a substitute for advice from a clinician.

Frequently asked questions

Why does my smartwatch give a different calorie number?

A wearable estimates energy actually expended, using heart rate and movement. These calculators estimate a baseline metabolic rate and multiply it by a self-reported activity level. They are answering different questions and will not agree.

Is BMI a good measure of health?

It is a population screening measure, not an individual diagnosis. It uses only height and weight, so it cannot distinguish muscle from fat and is known to misclassify athletes, older adults and some ethnic groups.

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