Sports Calculators
Heart Rate Zones Calculator
Calculate Zone 2, max-HR, and Karvonen heart-rate-reserve zones for general fitness planning.
Enter the values and review the result.
Used to estimate max heart rate as 220 - age when a known max is not entered.
Required for the Karvonen heart-rate-reserve method.
Leave blank to estimate max heart rate as 220 - age.
Simple uses max HR percentages. Karvonen also uses resting heart rate.
Used for guidance only; it does not change the zone math.
Calculation assumptions
- *Estimated max heart rate uses 220 - age unless you enter a known max heart rate.
- *Simple zones use percentages of max heart rate. Karvonen zones use heart-rate reserve: max HR - resting HR.
- *Zone ranges are general fitness estimates and can differ from lab testing, wearable zones, or coaching plans.
- *Medication, heat, fatigue, stress, sleep, hydration, pregnancy, and health conditions can change heart-rate response.
- *If you have symptoms, cardiac risk, pregnancy concerns, or a medical condition, ask a qualified professional before relying on training zones.
Enter your values and press Calculate.
Results and breakdowns will appear here after a valid calculation.
What are heart rate zones?
Heart rate zones split exercise intensity into ranges. Lower zones feel easier and are often used for warmups, recovery, and steady aerobic work. Higher zones feel harder and are usually used for shorter efforts.
Use the calculator above to estimate your zones, then compare the result with how the workout feels. The talk-test cue is often easier to use during a run, ride, walk, or gym session than staring at a watch every few seconds.
Zone 2 heart rate explained
Zone 2 is the easy aerobic range in this calculator: 60-70% intensity by the selected method. Many people use it for steady endurance work because the effort should feel controlled, repeatable, and conversational.
A practical cue is simple: if you cannot speak in full sentences, you may be drifting above Zone 2. Slow down, reduce incline, or take a short easy segment if your heart rate keeps climbing.
Karvonen method vs max heart rate method
The simple method applies each zone percentage directly to max heart rate. It is quick and works with only age or a known max heart rate.
The Karvonen method uses heart-rate reserve: max HR - resting HR. It can feel more personalized because two people with the same age but different resting heart rates can get different target ranges.
Try both methods if you are comparing estimates. If you have a tested max heart rate, enter it instead of relying only on 220 - age.
Practical examples
Age 30, simple method
Estimated max HR is 190 BPM. Zone 2 at 60-70% is about 114-133 BPM.
Age 40, Karvonen method
With resting HR 60, estimated max HR is 180 and reserve is 120. Zone 2 is about 132-144 BPM.
Resting heart rate changes
In Karvonen, a lower resting HR changes heart-rate reserve, so target zones can shift even when age stays the same.
Known max HR
If a reliable test or training data shows your max HR differs from 220 - age, enter the known value for a better estimate.
Heart rate zones by age
Age-based charts are shortcuts. A 30-year-old using 220 - age gets an estimated max of 190 BPM, while a 50-year-old gets 170 BPM. Real max heart rate varies, so age-based zones are a starting point rather than a rule.
For broader planning, pair this page with the Calorie Calculator, Macro Calculator, BMI Calculator, Body Fat Calculator, and Ideal Weight Calculator.
Common mistakes
- Using Zone 2 as a race pace instead of an easy, sustainable range.
- Entering a resting heart rate measured after caffeine, stress, or activity.
- Assuming 220 - age is exact for every person.
- Ignoring heat, hills, fatigue, illness, sleep, hydration, or medication effects.
- Training hard because a watch says a zone is low, even when effort feels unusually difficult.
Accuracy and limitations
This calculator is for general fitness planning only. It does not diagnose health conditions, prescribe exercise, or replace medical, clinical, or coaching advice.
If you have a heart condition, chest pain, dizziness, unusual shortness of breath, fainting, medication that affects heart rate, pregnancy concerns, or cardiac risk factors, ask a qualified professional before using heart-rate zones for training decisions.
Quick answers
What this calculator answers
- Want general calorie context?: Compare training estimates with calorie, macro, BMI, body fat, and ideal-weight planning tools. Health & Fitness calculators
- Training pace matters too: Heart rate is one signal. Pace, breathing, terrain, heat, and fatigue can all change workout intensity. Read the heart-rate training guide
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Results depend on the values you enter and any simplified assumptions used by the tool. Verify important results before making decisions or submitting official information.
Reference check
Sources and references
These references provide background context for the topic. They do not replace official advice or documents for personal decisions.
- Target heart rate guidance
American Heart Association
- Measuring physical activity intensity
CDC
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Enter your age.
Choose simple max heart rate percentage or Karvonen heart-rate reserve.
Enter resting heart rate if you choose Karvonen.
Optionally enter a known max heart rate from testing or reliable training data.
Review the Zone 2 highlight and the full 5-zone table.
Related Tools
Other helpful tools in the Sports Calculators category.
Calorie Calculator
Estimate BMR, TDEE, maintenance calories, and simple deficit or surplus planning targets.
Macro Calculator
Estimate daily protein, carbs, fat, calories, and macro split targets from body stats, goals, and activity.
BMI Calculator
Calculate body mass index from height and weight, see the adult category, and understand screening limitations.
Body Fat Calculator
Estimate body fat percentage with Navy circumference or BMI-based methods, reference ranges, and neutral context.
Ideal Weight Calculator
Compare common ideal-weight formulas with a healthy BMI range and clear estimate limitations.
Max Heart Rate Calculator
Estimate your maximum heart rate based on age.
Water Intake Calculator
Estimate daily water intake from body weight, activity, climate, and pregnancy or breastfeeding inputs.
Sleep Calculator
Estimate bedtime or wake-up times from sleep-cycle timing for general schedule planning.
Frequently Asked Questions
Common questions about Heart Rate Zones Calculator and how to read the result.
What is Zone 2 heart rate?
In this calculator, Zone 2 is 60-70% intensity by the selected method. It should usually feel easy, steady, and conversational.
Which method should I use?
Use the simple method if you only know age or max heart rate. Use Karvonen if you also know resting heart rate and want a heart-rate-reserve estimate.
What is the Karvonen formula?
Karvonen target HR = resting HR + (max HR - resting HR) x intensity. It uses heart-rate reserve instead of only max heart rate.
Should I enter a known max heart rate?
Yes, if it comes from reliable testing or training data. Otherwise the calculator estimates max heart rate as 220 - age.
Are heart rate zones exact?
No. They are estimates and can differ from lab-tested thresholds, wearable-device zones, or coach-defined training plans.
Can medication affect heart rate zones?
Yes. Some medications and health conditions affect heart-rate response. Ask a qualified professional if this applies to you.
Why does Zone 2 feel too easy or too hard?
Age formulas are averages. Heat, hills, fatigue, stress, hydration, sleep, and individual physiology can all change how a zone feels.
Is this medical advice?
No. This is an educational fitness estimate and should not be used to diagnose, treat, prevent, or manage a medical condition.