Body & Weight Calculators & Trackers

Calculate adult BMI from height and weight, show the CDC adult category, and explain why BMI is a screening measure rather than a diagnosis.

Calculate BMI-for-age for ages 2–19 using CDC sex-specific growth-chart data and report percentile/category without applying adult thresholds.

Estimate the adult body-weight range corresponding to BMI 18.5–24.9 for a supplied height.

Compare Devine, Robinson, Miller and Hamwi reference-weight formulas rather than presenting one “perfect” weight.

Estimate adult body-fat percentage with the Deurenberg BMI-age-sex model and show its uncertainty and limitations.

Run Step 1 of the current U.S. Navy body-composition assessment using waist-to-height ratio, then see whether the official Step 2 lookup is required.

Calculate the current U.S. Army waist-to-height ratio standard from waist at the navel and height, to three decimal places.

Compare established lean-body-mass equations and show estimated fat-free mass in kilograms and pounds.

Calculate fat-free mass index and height-normalized FFMI from height, weight and body-fat percentage.

Calculate a reference adjusted body weight for educational comparison only, never for medication dosing.

Calculate Body Adiposity Index from hip circumference and height and explain the model’s population limitations.

Estimate Relative Fat Mass from height, waist circumference and sex using the published RFM equation.

Calculate waist-to-hip ratio and provide neutral, source-controlled context without turning the ratio into a diagnosis.

Calculate waist-to-height ratio as a simple anthropometric ratio and keep military thresholds separate from general health context.

Calculate Body Roundness Index from waist circumference and height with the published BRI equation.

Calculate Ponderal Index from mass and height cubed and explain how it differs mathematically from BMI.

Calculate a height-to-wrist ratio and show legacy frame-size categories only as a non-clinical heuristic.

Estimate total body water with the Watson equations and show liters plus percentage of body weight.

Calculate absolute and percentage weight change from starting and current weight with neutral gain/loss wording.

Track weight privately on this device with dated entries, local trends, export and explicit delete-all controls.