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Heart Rate · Aerobic Base Training
Compare two clearly identified heart-rate methods for estimating a Zone 2 training range: percentage of maximum heart rate and Karvonen heart-rate reserve.
Estimate your range
The default maximum-heart-rate estimate uses the Tanaka equation. If you have an appropriate measured or otherwise established maximum, you can use that instead.
Method comparison
This finder deliberately does not combine the methods. Each answers the heart-rate question differently.
Zone 2 = 60–70% × HRmax
Applies the selected percentages directly to maximum heart rate. Resting heart rate does not change this range.
Target HR = Resting HR + (% × HRR)
Uses the difference between maximum and resting heart rate, then adds resting HR back after applying 60–70%.
Metabolic context
“Zone 2” can refer to different models. A formula-based bpm range is useful for training organization, but it does not directly measure lactate, gas exchange, Fatmax, mitochondrial function, or the first ventilatory threshold.
Individual physiological thresholds can fall above or below generic percentage bands.
At a sustainable aerobic effort, conversation is usually possible in phrases or sentences. Perceived effort can complement heart-rate data.
Heat, dehydration, fatigue, altitude, stress, illness, caffeine, medications, and sensor error can shift bpm at the same workload.
Compare heart rate, pace or power, and perceived effort under similar conditions over time.
Worked example
Using the default Tanaka HRmax estimate, the same person receives different Zone 2 ranges because the formulas treat resting heart rate differently.
HRmax = 208 − (0.7 × 35) = 183.5 bpm
HRR = 183.5 − 60 = 123.5 bpm
Neither result is presented as universally exact; each belongs to its own convention.
Input quality
Karvonen results are sensitive to resting HR. Use a representative value rather than a pulse taken after exercise, rushing, caffeine, or acute stress.
Morning before getting out of bed is commonly used because conditions are easier to repeat.
A short multi-day pattern can be more representative than one unusually high or low reading.
A chest strap, validated wearable, or careful manual pulse count can be used consistently.
Fitness, illness, medication, sleep, and stress can alter resting and exercise heart rate over time.
Aerobic-base training
Aerobic-base sessions are generally organized around controlled, repeatable work rather than maximal effort.
Increase duration or frequency progressively based on recovery and overall training load instead of chasing a higher heart rate.
At a similar heart rate, improved pace or cycling power over time can provide useful context about aerobic progress.
If heat, fatigue, illness, altitude, or poor recovery raises heart rate, use effort and symptoms rather than forcing a formula target.
Related tools
Tool guide
Use these tool-specific notes to understand the method, enter better data, interpret the output, and apply the result appropriately.
The finder shows Zone 2 using both 60–70% of HRmax and 60–70% of heart-rate reserve. The methods are displayed separately because they are different training-zone conventions.
Enter age, resting HR, and either the default predicted maximum or a relevant custom HRmax. Resting HR only affects the Karvonen/HRR method.
Do not average the two results. Use the method that matches your training plan and recognize that either range may differ from your individual physiological thresholds.
Use breathing, talk-test feel, pace/power stability, and longer-session heart-rate drift as context. Formula-based Zone 2 is not a direct measurement of lactate threshold or Fatmax.
Frequently asked questions
Practical answers about this tool's inputs, method, results, limitations, and common real-world use.
No. Zone systems are not standardized. This finder uses 60–70% specifically as the Zone 2 band in two common five-zone conventions and labels the method beside every result.
Karvonen applies the percentage to heart-rate reserve and then adds resting HR back. With a resting HR above zero, its 60–70% range will normally sit above 60–70% of maximum HR.
This calculator does not declare a universal winner. Both are estimates. Individual thresholds may differ from either range, especially when HRmax itself is estimated from age.
Yes. Choose the custom max-HR option when you have a value that is appropriate to your training context. The same maximum is then used in both displayed methods.
Not necessarily. Fat oxidation varies by person and workload, and formula-based heart-rate bands do not directly measure Fatmax or substrate use.
Some medications and health conditions alter resting or exercise heart-rate response. Generic percentage targets may be misleading, so individualized guidance can be more appropriate.
It can provide useful field context: sustainable conversational breathing generally suggests lower aerobic intensity. It is not a perfect substitute for measured thresholds, but it can help identify obviously mismatched heart-rate targets.
Heat, dehydration, fatigue, and prolonged exercise can raise heart rate even when pace or power stays constant. You may need to reduce output to remain within a chosen heart-rate range.
Use the calculated range as a reference, but expect heart rate to respond differently in heat. Pace or power that fits the range in cool conditions may drive a higher heart rate when it is hot.
A formula assigns a percentage range from heart-rate inputs. Laboratory testing can identify individual ventilatory, lactate, or metabolic responses, which may fall above or below a generic percentage band.
References
Content reviewed: .
This calculator provides general fitness education and formula-based estimates. It does not diagnose a condition, measure metabolic thresholds, determine exercise safety, or prescribe a medically appropriate heart-rate range. Stop exercise and seek appropriate care for concerning symptoms. People with cardiovascular disease, significant illness, pregnancy, rehabilitation needs, or medications that affect heart rate should use individualized professional guidance where appropriate.