Heart Rate Zone Calculator
Find your target training zones for fat burn, cardio fitness, and peak performance
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Enter your age to see all 5 training zones. Adding your resting heart rate enables the more precise Karvonen formula.
What Are Heart Rate Training Zones?
When you exercise, your heart rate increases. Heart rate zones are ranges that correspond to different exercise intensity levels, typically defined as percentages of your maximum heart rate. Training within specific zones helps you target different fitness goals.
The 5 Training Zones
- Zone 1 (50-60%): Very light effort. Used for warm-up, cool-down, and active recovery days. You can easily hold a conversation.
- Zone 2 (60-70%): Light effort. The primary fat-burning zone. Ideal for building an aerobic base and long, steady workouts. You can talk comfortably.
- Zone 3 (70-80%): Moderate effort. Improves cardiovascular fitness and aerobic capacity. Breathing becomes heavier; talking is possible but harder.
- Zone 4 (80-90%): Hard effort. Trains your anaerobic threshold. You can only say short phrases. Sustained for 10-30 minute intervals.
- Zone 5 (90-100%): Maximum effort. Only sustainable for short bursts (30 seconds to 3 minutes). Used for sprints and high-intensity intervals.
Heart Rate Calculation Methods
Maximum Heart Rate: Fox Formula
The simplest and most widely used formula: Max HR = 220 − age. For example, a 30-year-old has an estimated max HR of 190 bpm. This is an approximation; your actual max can vary by 10-15 bpm.
Basic Percentage Method
Calculates zones as a direct percentage of max HR. Simple but less personalized. Used when resting heart rate is not provided.
Target HR = Max HR × intensity percentage
Karvonen Formula (Heart Rate Reserve)
A more accurate method that accounts for your fitness level by incorporating resting heart rate:
Target HR = Resting HR + (intensity × (Max HR − Resting HR))
The term (Max HR − Resting HR) is called your Heart Rate Reserve (HRR). A lower resting HR (indicating better fitness) results in different zone boundaries, making this method more personalized.
How to Measure Resting Heart Rate
Your resting heart rate (RHR) is your pulse when you're completely at rest. It's an indicator of cardiovascular fitness — a lower RHR generally means better fitness.
Measurement Instructions
- Measure first thing in the morning before getting out of bed
- Place two fingers (index and middle) on the side of your neck or inside of your wrist
- Count the beats for 60 seconds (or 30 seconds and multiply by 2)
- Repeat for 3 mornings and take the average for the most accurate reading
Typical Resting Heart Rates
- Athletes: 40-60 bpm
- Excellent fitness: 55-65 bpm
- Good fitness: 60-70 bpm
- Average: 70-80 bpm
- Below average: 80-100 bpm
A resting heart rate consistently above 100 bpm (tachycardia) should be discussed with your doctor.
Training Guide by Goal
Weight Loss / Fat Burning
Zone 2 (60-70%) is the traditional "fat-burning zone" because the body uses a higher percentage of fat for fuel at lower intensities. However, higher-intensity exercise burns more total calories. A mix of Zone 2 base work and Zone 3-4 intervals is most effective for weight loss.
Cardiovascular Fitness
Zone 3 (70-80%) is the sweet spot for improving cardiovascular fitness. Aim for 30-60 minutes in this zone, 3-5 days per week. This strengthens your heart muscle and improves oxygen delivery to working muscles.
Endurance Training
Follow the 80/20 rule used by elite endurance athletes: spend 80% of training time in Zones 1-2 (easy, conversational pace) and 20% in Zones 4-5 (hard intervals). This builds a strong aerobic base while developing speed.
Safety Tips
- Always warm up in Zone 1-2 for 5-10 minutes before intense exercise
- If you feel dizzy, nauseous, or chest pain, stop immediately
- New to exercise? Stay in Zone 1-2 for the first 4-6 weeks
- Use a heart rate monitor or fitness tracker for real-time feedback
- Stay hydrated during all exercise sessions
Frequently Asked Questions
The 220-age formula provides a reasonable estimate but can be off by 10-15 bpm for individuals. It's a population average, not personalized. For more precise results, consider a max HR test with a healthcare professional, or use the Karvonen method by entering your resting heart rate.
The basic method simply takes a percentage of your max HR. Karvonen uses your Heart Rate Reserve (max HR minus resting HR) to account for your fitness level. A very fit person with a low resting HR will get different zone boundaries than an unfit person of the same age. Karvonen is more personalized and generally considered more accurate.
It's not a myth, but it's commonly misunderstood. At lower intensities (Zone 2), your body uses a higher percentage of fat for fuel. However, higher-intensity exercise burns more total calories per minute. For weight loss, the total calorie deficit matters more than the fuel source. A combination of Zone 2 work and higher-intensity intervals is most effective.
Yes. Beta-blockers and some other cardiac medications can significantly lower your maximum and resting heart rate, making standard zone calculations inaccurate. If you take heart medications, consult your doctor for personalized target heart rate ranges rather than relying on general formulas.
Zone 1-2: Can sustain for hours (recovery, long runs). Zone 3: 30-60 minutes (tempo runs, steady cardio). Zone 4: 10-30 minutes total (intervals). Zone 5: Only 30 seconds to 3 minutes per interval (sprints). The right distribution depends on your goals — see the Training Guide tab above.
Resting heart rate is one of the simplest indicators of cardiovascular fitness. A lower RHR means your heart pumps more blood per beat and doesn't need to beat as often. As your fitness improves, your RHR typically decreases. Entering it also enables the more accurate Karvonen formula for zone calculation.
⚠ Medical Disclaimer
These heart rate zones are estimates based on standard formulas. Your actual maximum heart rate and safe training zones may differ. If you're new to exercise, have a heart condition, take medications that affect heart rate, or experience chest pain, dizziness, or shortness of breath during exercise, consult your doctor before following these guidelines.
References & Sources
- Fox SM, Naughton JP, Haskell WL (1971). Physical activity and the prevention of coronary heart disease. Annals of Clinical Research, 3, 404-432. (220-age formula)
- Karvonen MJ, Kentala E, Mustala O (1957). The effects of training on heart rate; a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae, 35(3), 307-315.
- American Heart Association. Target Heart Rates Chart. heart.org
- American College of Sports Medicine (ACSM). Guidelines for Exercise Testing and Prescription, 11th Edition.
- Seiler S (2010). What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5(3), 276-291.