Health Calculators

Everyday health and fitness math using standard published formulas — for general information only, not medical advice.

Heart Rate Zones Calculator

Age (years)

Estimate your maximum heart rate and the five common training zones from your age.

Waist (cm) Hip (cm)

Compute the waist-to-hip ratio used in body shape and fitness tracking.

First day of last period

Estimate a due date by adding 280 days to the last period, the standard Naegele method.

Height (cm) Weight (kg)

Calculate body surface area with the widely used Mosteller square-root formula.

Formula Height (cm) Weight (kg)

Estimate lean body mass with the Boer formula and see the fat mass remainder.

Steps Stride length (m)

Convert a step count into kilometres, metres and miles using your stride length.

Packs per day Price per pack Years

See what smoking costs per week, per year and over the years — a powerful motivator.

Child Mother height (cm) Father height (cm)

Estimate a child's future adult height with the classic mid-parental method.