Target Heart Rate Calculator
Find your optimal heart rate zones for effective exercise
How to Use This Target Heart Rate Calculator
- Enter your age (used to estimate maximum heart rate)
- Optionally enter your resting heart rate for more accurate zones (Karvonen method)
- Click 'Calculate Zones' to see all five training zones
- Use the fat-burning zone (50-70%) for easy days and cardio zone (70-85%) for improvement
Example: Age 35, resting HR 65 bpm. Max HR: 185 bpm. Zone 2 (fat burn): 125-149 bpm. Zone 3 (cardio): 149-161 bpm. Zone 4 (threshold): 161-173 bpm. For a 45-minute easy run, stay in Zone 2 (125-149 bpm).
Tip: Wear a heart rate monitor during a few workouts to learn how different effort levels feel. Eventually you'll be able to estimate your zone by perceived effort without checking your watch constantly.
Why Use a Target Heart Rate Calculator?
Heart rate zones turn vague workout intensity into objective, measurable targets. Training in the right zone for your goal makes every workout more effective.
- Train at the right intensity to actually improve cardiovascular fitness
- Prevent overtraining by keeping easy days truly easy
- Maximize fat oxidation during longer, lower-intensity sessions
- Push hard enough during interval workouts to trigger adaptation
- Recover properly between hard sessions
- Monitor cardiovascular health and fitness improvements over time
Understanding Your Results
Results display your maximum heart rate and five training zones, each with a specific purpose and heart rate range.
| Result | Meaning | Action |
|---|---|---|
| Zone 1: 50-60% of max (Recovery) | Very light effort - conversational pace | Use for warm-ups, cool-downs, and active recovery days |
| Zone 2: 60-70% of max (Fat Burn/Endurance) | Light effort - can talk in full sentences | Build aerobic base; majority of training volume should be here |
| Zone 3: 70-80% of max (Aerobic/Cardio) | Moderate effort - can speak but prefer not to | Improves cardiovascular efficiency; tempo runs and sustained efforts |
| Zone 4: 80-90% of max (Anaerobic/Threshold) | Hard effort - only short phrases possible | Lactate threshold training; improves speed and power |
| Zone 5: 90-100% of max (VO2 Max) | Maximum effort - cannot speak | Brief intervals only; develops peak performance capacity |
Meaning: Very light effort - conversational pace
Action: Use for warm-ups, cool-downs, and active recovery days
Meaning: Light effort - can talk in full sentences
Action: Build aerobic base; majority of training volume should be here
Meaning: Moderate effort - can speak but prefer not to
Action: Improves cardiovascular efficiency; tempo runs and sustained efforts
Meaning: Hard effort - only short phrases possible
Action: Lactate threshold training; improves speed and power
Meaning: Maximum effort - cannot speak
Action: Brief intervals only; develops peak performance capacity
Note: The Karvonen method (using resting heart rate) gives more personalized zones because it accounts for your current fitness level. As you get fitter, your resting HR drops, shifting all zones accordingly.
About Target Heart Rate Calculator
Formula
Max HR = 220 - Age | Karvonen Zone = ((Max HR - Resting HR) × Zone %) + Resting HR The 220-minus-age formula estimates maximum heart rate (actual max varies significantly between individuals). Karvonen's formula uses heart rate reserve (the difference between max and resting) to calculate zones, which is more accurate for trained individuals whose resting HR has dropped.
Current Standards: The American College of Sports Medicine defines moderate intensity as 64-76% of max HR and vigorous as 77-95%. For building aerobic fitness, 150 minutes/week of moderate or 75 minutes of vigorous activity is recommended. Elite endurance athletes typically spend 80% of training in Zone 2.
Frequently Asked Questions
Is 220-minus-age accurate for maximum heart rate?
It's an estimate with significant individual variation (standard deviation of about 10-12 bpm). Some 40-year-olds have max HR of 165 while others hit 195. If you've seen your heart rate exceed the formula's prediction, your true max is higher. The gold standard is a graded exercise test, but you can estimate from your highest recorded heart rate during all-out effort. The formula works as a starting point.
What's the best zone for burning fat?
Zone 2 (60-70%) maximizes the percentage of calories from fat, but higher zones burn more total calories (and thus more total fat). For a 45-minute workout: Zone 2 might burn 400 calories (60% fat = 240 fat calories). Zone 4 might burn 600 calories (35% fat = 210 fat calories). The difference is minimal, and higher intensity has post-workout metabolic benefits. Train in the zone that matches your goal - fat burn zone is about building aerobic base, not necessarily losing weight fastest.
Why should most of my training be in Zone 2?
Zone 2 builds mitochondrial density (cellular powerhouses), capillary networks, and aerobic enzyme efficiency without accumulating fatigue that requires recovery. It's the foundation that allows you to recover between hard efforts and handle more training volume. Elite endurance athletes train 80% easy (Zone 2) and 20% hard (Zone 4-5), avoiding the moderate 'gray zone' that's too stressful to recover from quickly but not hard enough to maximize adaptation.
How do I know if my zones are set correctly?
In Zone 2, you should be able to hold a conversation (the 'talk test'). Zone 4 should feel 'comfortably hard' - sustainable for 20-60 minutes with focus. Zone 5 should be unsustainable beyond a few minutes. If easy runs leave you exhausted, your Zone 2 ceiling might be set too high. If you can chat during 'threshold' workouts, your zones might be too low. Adjust based on perceived effort, not just the formula.
My heart rate seems too high/low for how I feel. What's wrong?
Heart rate is affected by caffeine, sleep quality, stress, dehydration, heat, altitude, and illness. A higher-than-normal HR at a given effort usually indicates incomplete recovery, dehydration, or oncoming illness. Lower-than-normal HR could indicate overreaching (chronic fatigue). Use HR as one data point alongside perceived effort. If they consistently disagree, your zones may need recalibration based on actual testing rather than age-based formulas.