Measure resting HR consistently
Use a calm, repeatable condition rather than a pulse taken immediately after activity, caffeine, or stress.
Heart Rate · Karvonen HRR Method
Target Heart Rate Zones (Karvonen)
Calculate five personalized training zones from heart rate reserve using your resting heart rate and either an age-predicted or custom maximum heart rate.
5 HRR zonesTanaka max-HR estimateMeasured max override
Calculate your zones
Enter age and resting heart rate
Use a calm resting pulse, ideally measured when you are rested. The default maximum-heart-rate estimate uses the Tanaka equation. If you have an appropriate measured maximum, switch to custom.
ImportantAge-predicted max HR is an estimate with individual variation. These zones are training guidance, not a diagnosis or medical clearance.
Your five heart-rate zones will appear here.Enter your values and calculate. With JavaScript enabled, results update instantly without reloading.
Method
How the Karvonen calculation works
First, calculate heart rate reserve by subtracting resting heart rate from maximum heart rate. Then multiply that reserve by an intensity fraction and add resting heart rate back.
This page uses five adjacent HRR bands: 50–60%, 60–70%, 70–80%, 80–90%, and 90–100%. They are a practical way to display training ranges; different coaching systems may use different boundaries or labels.
Example: age 35, resting HR 60
Estimated HRmax = 208 − (0.7 × 35) = 183.5 bpmHRR = 183.5 − 60 = 123.5 bpmZone 2 low = 60 + (123.5 × 0.60) ≈ 134 bpmZone 2 high = 60 + (123.5 × 0.70) ≈ 146 bpmUsing the result
Treat heart-rate zones as a guide, not an absolute rule
Heart rate responds to temperature, hydration, fatigue, stress, altitude, medications, illness, and measurement error. Perceived effort and workout context still matter.
Prefer measured max HR when appropriate
Age equations describe population averages. A properly obtained individual maximum can differ from the estimate.
Do not chase a number at the expense of symptoms
Slow down or stop when exercise feels unsafe or symptoms are concerning, regardless of the displayed zone.
Account for medications and health conditions
Some medications, especially those that affect cardiovascular response, can make standard heart-rate targets less useful.
Related fitness tools
Connect heart rate with cardio training
Tool guide
Understand and use the Target Heart Rate Zones (Karvonen)
Use these tool-specific notes to understand the method, enter better data, interpret the output, and apply the result appropriately.
Heart-Rate Reserve
Karvonen uses heart-rate reserve: HRmax minus resting HR. A target is resting HR plus a chosen fraction of that reserve.
Measure Resting HR
Use a calm resting measurement collected under consistent conditions. A noisy or unusually elevated resting value shifts every calculated zone.
Choose HRmax
The calculator can use an age-predicted maximum or an appropriate custom value. Error in HRmax changes the heart-rate reserve and therefore every zone boundary.
Use Zones Flexibly
Five-zone percentage bands are training conventions. Heat, dehydration, altitude, fatigue, medication, and individual thresholds can make a real training response differ from the calculated range.
Frequently asked questions
Target Heart Rate Zones (Karvonen) FAQs
Practical answers about this tool's inputs, method, results, limitations, and common real-world use.
What is heart rate reserve?
Heart rate reserve (HRR) is the difference between maximum heart rate and resting heart rate. Karvonen targets apply an intensity percentage to that reserve and then add resting heart rate back.
Why use Tanaka instead of 220 minus age?
The default uses the Tanaka equation, 208 − 0.7 × age, because it was derived from a large meta-analysis and validation sample in healthy adults. It is still an estimate, not an individual measurement.
Is Zone 2 always 60–70% HRR?
No. Zone systems vary. This calculator uses 60–70% HRR for its five-zone display, while other training frameworks may set different boundaries.
Should I use resting HR from my smartwatch?
You can use a representative resting value from a reliable device or manual measurement. Consistency matters, and wearable algorithms can differ between products.
What if my calculated maximum looks wrong?
Age-based formulas can overestimate or underestimate an individual. Use the custom maximum option only when you have a value that is appropriate for your training context.
Can these zones replace medical advice?
No. They are informational training ranges. People with symptoms, cardiovascular conditions, or medicines affecting heart rate may need individualized guidance.
When should I measure resting heart rate for Karvonen zones?
A quiet morning measurement before caffeine or exercise is often practical. Use the same method across several days if you want a stable baseline rather than relying on one unusual reading.
Can I use a measured maximum heart rate instead of an age formula?
Yes when the value comes from an appropriate test and is relevant to your exercise mode. Entering a credible measured maximum can remove one source of prediction error.
Why are Karvonen zones different from percent-of-max zones?
Karvonen applies intensity to the reserve between resting and maximum heart rate, then adds resting HR back. Percent-of-max simply multiplies HRmax, so the numeric ranges are different.
Are the five Karvonen zones the same as lactate or ventilatory thresholds?
Not necessarily. Percentage zones are convenient training conventions, while physiological thresholds are individual responses measured or estimated by other methods.
References
Formula and heart-rate guidance sources
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study (1957).
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited (2001).
- American Heart Association: Target Heart Rates Chart.
Content reviewed: .
Health & training note
This calculator provides general fitness information. Maximum-heart-rate equations and target zones are estimates and may not reflect an individual’s safe or optimal exercise intensity. Heart conditions, symptoms, medications, pregnancy, illness, and other factors can change appropriate heart-rate guidance.