Health numbers only help if you know where they came from. A body-fat figure from a bathroom scale’s guesswork, a training zone copied from a poster, or a step count with no stride length behind it can all mislead. The calculators below use the standard published methods — and name them — so you can see exactly what your result is based on and how far to trust it.
Nothing you enter is uploaded or stored: your measurements are processed on your device and forgotten when you close the tab. Treat every result as a well-founded estimate for training and curiosity, and take anything health-critical to a professional.
Which health calculator do you need?
For body composition, the body fat calculator needs only a tape measure. For training, the heart rate zones calculator builds your zones from max and resting heart rate. Walkers: the steps to calories calculator and steps to miles calculator turn a step count into energy and distance using your stride. Waking up groggy? The sleep cycle calculator times bedtime to complete full cycles. And for the family questions, the child height predictor estimates adult height from parents’ heights, while the dog age calculator converts by breed size, not the old one-size myth.
Fitness & Body
Body composition, training zones, step-based energy and distance, and growth prediction — the numbers behind a training plan.
Body Fat Calculator
Navy-method body fat % from a tape measure.
Heart Rate Zones Calculator
Your training zones with the Karvonen formula — Zone 2 included.
Steps to Calories Calculator
Steps to calories burned — weight & pace adjusted, both directions.
Steps to Miles Calculator
Convert steps to miles & km using your own stride length.
Child Height Predictor
How tall will your child be? Pediatrician's formula.
Sleep & Pets
Sleep timing built on complete cycles, and honest dog-age conversion by breed size.
Sleep Cycle Calculator
Wake up refreshed — ideal bedtimes in 90-minute cycles.
Dog Age Calculator
Dog (and cat) age in human years by breed size.