What is Zone 2 cardio and why is it so popular for longevity?

Zone 2 training occurs at 60% to 70% of heart rate reserve, where your body primarily burns fatty acids through mitochondrial aerobic respiration while producing minimal lactate. High-volume Zone 2 training builds cellular mitochondrial density, cardiovascular efficiency, and metabolic health.

What is the Karvonen formula?

The Karvonen formula calculates Target Heart Rate (THR) as: THR = [(HRmax - HRrest) × % Intensity] + HRrest. By factoring in your individual resting heart rate (HRrest), it provides substantially more personalized workout zones than simple percentages of maximum heart rate.

What is a normal resting heart rate?

A normal resting heart rate for healthy adults ranges from 60 to 100 beats per minute. Well-trained endurance athletes often have resting heart rates between 40 and 60 bpm.

How does age affect maximum heart rate?

As humans age, the sinoatrial node in the heart naturally slows, and adrenergic receptor sensitivity declines, causing maximum achievable heart rate to decrease by roughly one beat per year.

Is my heart rate and age data stored?

No. All calculations are executed locally inside your web browser using JavaScript. No personal biometric details are ever transmitted or saved.

Target Heart Rate Zone Calculator

Calculate your 5 cardio training zones, Zone 2 fat burning range, and Maximum Heart Rate using Karvonen & Tanaka formulas.

100% free
Private in browser
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Quick Age Presets:

Your Age (Years)

Resting Heart Rate (BPM)

Estimated HRmax (Tanaka)

187 bpm

208 - (0.7 × 30)

Zone 2 Endurance Range

138 – 150 bpm

Optimal aerobic fat burn pace

Heart Rate Reserve (HRR)

122 bpm

HRmax - RHR

Personalized 5-Zone Intensity Spectrum (Karvonen)

Zone 1: Active Recovery (50%–60%)Easy warm up, walking, active recovery

126 – 138 BPM

Zone 2: Aerobic Base & Fat Burn (60%–70%)Mitochondrial building, all-day fat oxidation pace

138 – 150 BPM

Zone 3: Tempo Aerobic Fitness (70%–80%)Moderate tempo, aerobic endurance, cardiovascular health

150 – 163 BPM

Zone 4: Anaerobic Threshold (80%–90%)Hard threshold, lactate buildup, high speed endurance

163 – 175 BPM

Zone 5: VO2 Max & Peak Power (90%–100%)Maximum sprint effort, VO2 max intervals, peak output

175 – 187 BPM

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About Target Heart Rate Zone Calculator

The Target Heart Rate Zone Calculator helps athletes, runners, and fitness enthusiasts calibrate cardiovascular workouts for maximum physiological adaptation. By combining your age and resting pulse through the Karvonen Heart Rate Reserve (HRR) formula, this tool identifies your personalized beats-per-minute ranges for Zone 2 mitochondrial endurance, aerobic tempo, and anaerobic threshold.

How to use Target Heart Rate Zone Calculator

Enter your current age in years.
Enter your resting heart rate (measure pulse for 60 seconds upon waking up).
Review your estimated Maximum Heart Rate via modern Tanaka and classic Fox formulas.
Inspect your 5 training intensity zones with exact beats per minute (BPM) boundaries.

Key features

Accurate Karvonen Heart Rate Reserve (HRR) personalized zone modeling
Zone 2 endurance & fat oxidation range highlighter for long-term health
Compares modern Tanaka formula ($208 - 0.7 \times \text{age}$) with classic Fox formula ($220 - \text{age}$)
100% private in-browser fitness calculations with zero telemetry

Frequently asked questions

What is Zone 2 cardio and why is it so popular for longevity?: Zone 2 training occurs at 60% to 70% of heart rate reserve, where your body primarily burns fatty acids through mitochondrial aerobic respiration while producing minimal lactate. High-volume Zone 2 training builds cellular mitochondrial density, cardiovascular efficiency, and metabolic health.
What is the Karvonen formula?: The Karvonen formula calculates Target Heart Rate (THR) as: THR = [(HRmax - HRrest) × % Intensity] + HRrest. By factoring in your individual resting heart rate (HRrest), it provides substantially more personalized workout zones than simple percentages of maximum heart rate.
What is a normal resting heart rate?: A normal resting heart rate for healthy adults ranges from 60 to 100 beats per minute. Well-trained endurance athletes often have resting heart rates between 40 and 60 bpm.
How does age affect maximum heart rate?: As humans age, the sinoatrial node in the heart naturally slows, and adrenergic receptor sensitivity declines, causing maximum achievable heart rate to decrease by roughly one beat per year.
Is my heart rate and age data stored?: No. All calculations are executed locally inside your web browser using JavaScript. No personal biometric details are ever transmitted or saved.

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