How the numbers work
The reasoning behind every zone Zonas shows you. Plain explanations, the formulas the app actually uses, and the sources behind them.
Heart Rate Zones
A plain explanation of Zonas heart rate zones, how the five labels work, and why weekly cardio goals use a separate moderate/vigorous model.
Read ScienceHow Zonas Calculates Your Zones
The full Zonas zone decision tree: max heart rate, resting heart rate, Karvonen, percent-HRmax fallback, custom boundaries, and weekly goals.
Read ScienceMax Heart Rate
How Zonas chooses maximum heart rate, why the app uses the Tanaka fallback, and when a custom max heart rate is better.
Read ScienceResting Heart Rate
How Zonas reads resting heart rate from Apple Health, why it uses a 14-day median, and what happens when resting heart rate is missing.
Read ScienceWeekly Cardio Goals
How Zonas separates workout zones from weekly moderate-equivalent cardio goals based on WHO and CDC-style guidance.
Read ScienceZone Calculation Methods
The three zone modes Zonas supports: Karvonen heart rate reserve, percent of max heart rate fallback, and custom boundaries.
Read