Most health tools give you a generic number. This one uses validated biomarker formulas (Uth VO₂max, Mifflin-St Jeor, WHO BMI) to estimate your biological age, cardio fitness percentile, and daily energy needs from your inputs. No signup to see your results. The free version gives you the full dashboard. For $4.99 (one-time, no subscription) you get a personalised 12-week training plan and downloadable PDF report with your HR training zones, calorie strategy, and a week-by-week roadmap.