Health & Fitness Calculators That Account For Your Real Data

BMI, TDEE, body fat, heart rate zones—each calculator uses the same clinical formulas nutritionists and physicians use, not one-size-fits-all shortcuts.

My mom Elena turned 62 in 2019. That fall we sat at her kitchen table in Sacramento with three different BMI tools open on my laptop—each gave her a different number, none of them accounted for her gestational diabetes history or the daily 45-minute walks she'd done since retiring. I got tired of watching her second-guess her doctor because random websites disagreed. I worked with a small team to build calculators grounded in the same clinical guidelines I use with people—the same ones I share with my own family. Whether you're tracking resting heart rate or estimating daily nutrient needs, every number here ties back to peer-reviewed research, plainly explained.