Calculators that match the app
Every calculator here uses the same math Zonas runs on your phone. Run the numbers in the browser, then carry them into a workout.
Calculator
Heart Rate Zone Calculator
The method behind the Zonas heart rate zone calculator, including Tanaka max HR, Karvonen zones, percent-HRmax fallback, and Swift-matching rounding.
Open CalculatorMax Heart Rate Calculator
The Zonas max heart rate calculator method: Tanaka HRmax, Swift-style truncation, custom overrides, and why max heart rate is only an estimate.
Open CalculatorTarget Heart Rate Calculator
How the Zonas target heart rate calculator uses Karvonen heart rate reserve to turn max heart rate, resting heart rate, and intensity into BPM.
Open CalculatorWeekly Cardio Minutes Calculator
The method behind the Zonas weekly cardio minutes calculator: moderate minutes plus two times vigorous minutes, compared with 150 and 300 minute targets.
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