How to Calculate Target Heart Rate & Zones

Introduction

Understanding your target heart rate is fundamental to effective cardiovascular training. Whether your goal is to improve endurance, burn fat, increase speed, or enhance overall fitness, training within specific heart rate zones ensures your workouts are both safe and optimally effective.

Why Heart Rate Training Matters

Maximise workout efficiency and time investment
Ensure safety during cardiovascular exercise
Target specific goals (fat burning, endurance, speed)
Track fitness progress objectively over time
Personalise training to your fitness level

Benefits of Zone-Based Training

Training within specific heart rate zones:

Improves cardiovascular health systematically
Burns fat efficiently in aerobic zones
Builds endurance through aerobic base training
Increases speed with anaerobic threshold work
Prevents overtraining and reduces injury risk

From Guesswork to Data-Driven Training

Learning how to calculate target heart rate transforms your exercise approach:

Replace guesswork with precise training targets
Use proven methods (220-age formula, Karvonen method)
Personalise intensity to your fitness level
Optimise every workout for specific goals
Track improvements with measurable data

What You'll Master

This guide covers:

Heart rate zone physiology and training benefits
Step-by-step calculations for both estimation methods
Practical application to real-world training
Zone targeting for different fitness goals
Training personalisation strategies

You'll be able to tailor every run, cycle, or cardio session to your precise fitness level and goals with confidence.

The Physiology of Heart Rate and Training Zones

Your heart rate is a direct reflection of your body’s oxygen demand during exercise. As intensity increases, your heart pumps faster to deliver more oxygen to working muscles. Training within specific heart rate zones targets different physiological adaptations:

Zone 1 (50–60% max HR): Active recovery, improves overall health
Zone 2 (60–70% max HR): Builds aerobic base, enhances fat burning
Zone 3 (70–80% max HR): Improves aerobic capacity and efficiency
Zone 4 (80–90% max HR): Increases lactate threshold for sustained speed
Zone 5 (90–100% max HR): Boosts peak performance and VO₂ max

To use these zones, you first need to estimate your maximum heart rate (MHR) and, for greater accuracy, your resting heart rate (RHR).

Method 1: Percentage of Maximum Heart Rate (%MHR)

This is the simplest approach, using only your age to estimate MHR.

MHR Estimation:
MHR = 220 – Age

Target Heart Rate for a Zone:
Target HR = % of Intensity × MHR

Example:
A 40-year-old’s estimated MHR = 220 – 40 = 180 bpm
Zone 2 (60–70%): 0.6 × 180 = 108 bpm to 0.7 × 180 = 126 bpm

Limitation: This method doesn’t account for fitness level—two 40-year-olds with different RHRs get the same zones.

Method 2: Karvonen Method (Heart Rate Reserve – HRR)

This personalised method factors in your RHR, which is a strong indicator of cardiovascular fitness.

Step 1: Calculate Heart Rate Reserve (HRR)
HRR = MHR – RHR

Step 2: Calculate Target Heart Rate
Target HR = (HRR × % of Intensity) + RHR

Example:
Same 40-year-old with RHR = 60 bpm:

HRR = 180 – 60 = 120
Zone 2 (60–70%): (120 × 0.6) + 60 = 132 bpm to (120 × 0.7) + 60 = 144 bpm

Advantage: Fitter individuals (lower RHR) get higher target zones, reflecting their greater capacity.

Finding Your True Resting Heart Rate (RHR)

For accuracy:

Measure first thing in the morning, before getting out of bed
Use a finger on your wrist (radial pulse) or neck (carotid pulse)
Count beats for 60 seconds (or 30 seconds × 2)
Repeat for 3–5 days and take the average

A normal RHR is 60–100 bpm; well-trained athletes often have RHRs of 40–50 bpm.

Step-by-Step Zone Calculation Process

Determine your age for MHR estimation
Measure your RHR over several mornings
Choose your method:
- Use %MHR for simplicity
- Use Karvonen for personalisation
Calculate zones for all five training intensities
Validate with the “Talk Test”:
- Zone 1–2: Can hold a full conversation
- Zone 3: Can speak in short phrases
- Zone 4–5: Can only say a few words

Pro Tips & Best Practices

Use a chest strap monitor: Optical wrist sensors can be inaccurate during high-intensity intervals
Reassess every 3–6 months: As fitness improves, RHR decreases—recalculate zones
Account for external factors: Caffeine, stress, heat, and dehydration elevate HR independently of effort
Don’t obsess over numbers: Use zones as a guide, but listen to your body—perceived exertion matters
Start in Zone 2: For beginners, 80% of training should be in Zone 2 to build aerobic capacity safely

Practical Applications

Endurance training: Long, slow runs in Zone 2 teach your body to burn fat efficiently
Interval training: Alternate Zone 4–5 efforts with Zone 1–2 recovery to boost VO₂ max
Fat loss: Zone 2 burns the highest percentage of fat calories (though total calories matter more)
Race pacing: Use Zone 3 for half-marathon pace, Zone 4 for 10K pace
Recovery: Active recovery days should stay in Zone 1 to promote blood flow without added stress

Practice Calculating Heart Rate Zones

Scenario 1: Basic %MHR Calculation

A 30-year-old athlete wants to calculate their zones.

MHR: 220 – 30 = 190 bpm
Zone 2 (60–70%): 114–133 bpm
Zone 4 (80–90%): 152–171 bpm

Scenario 2: Personalised Karvonen Calculation

The same 30-year-old has an RHR of 50 bpm.

HRR: 190 – 50 = 140
Zone 2: (140 × 0.6) + 50 = 134 bpm to (140 × 0.7) + 50 = 148 bpm
Zone 4: (140 × 0.8) + 50 = 162 bpm to (140 × 0.9) + 50 = 176 bpm

Insight: Karvonen zones are higher, reflecting the athlete’s fitness.

Scenario 3: Training Plan Design

A 45-year-old runner (RHR = 58 bpm) plans a 45-minute workout:

Warm-up (10 min): Zone 1 → (162 × 0.5) + 58 = 139 bpm
Main set (30 min): Zone 2 → (162 × 0.65) + 58 = 163 bpm
Cool-down (5 min): Zone 1 → 139 bpm

Scenario 4: Tracking Fitness Progress

After 6 months of training, the 30-year-old’s RHR drops from 50 to 45 bpm.

New HRR: 190 – 45 = 145
New Zone 2: (145 × 0.65) + 45 = 140 bpm
Interpretation: At the same heart rate (140 bpm), the effort now feels easier—proof of improved fitness.

What is the most accurate way to find my max heart rate?

The gold standard is a graded exercise test (GXT) in a clinical setting. However, field tests like a 3–5 km time trial (all-out effort) can provide a good estimate. Never attempt a true max HR test without medical clearance—it carries health risks.

Which method is better: %MHR or Karvonen?

Karvonen (HRR) is more accurate because it accounts for your individual fitness level via RHR. A fit person with a low RHR has a larger working range (HRR), and Karvonen reflects this. %MHR is a one-size-fits-all approach.

Why are my heart rate zones different on my watch?

Different devices use:

Different MHR formulas (e.g., 208 – 0.7 × age vs. 220 – age)
Different zone definitions (e.g., Zone 2 = 60–75% vs. 60–70%)
Different methods (%MHR vs. Karvonen)

Always check your device settings and ensure your age and RHR are correct.

My heart rate is higher than my zone, but the effort feels easy. Why?

Common causes:

Dehydration: Even mild dehydration increases HR
Heat/humidity: Your heart works harder to cool you
Caffeine/stimulants: Artificially elevate HR
Lack of recovery: Fatigue from prior workouts
Illness: Early signs of a cold can raise RHR

Use the Talk Test and Rate of Perceived Exertion (RPE) alongside HR data.

What is a good resting heart rate?

Normal: 60–100 bpm
Athletic: 40–59 bpm
Lower RHR generally indicates better cardiovascular fitness. Measure it first thing in the morning for accuracy.

Can I use these zones for all sports?

Your HR response varies by sport:

Running: Highest HR for a given effort (weight-bearing, full-body)
Cycling: ~10–15 bpm lower than running (non-weight-bearing)
Swimming: Hardest to measure due to water pressure on chest

Establish sport-specific zones if you train seriously in multiple disciplines.

How often should I recalculate my zones?

Recalculate every 3–6 months, or whenever you notice a sustained change in RHR. As fitness improves, your RHR decreases, shifting your zones upward.

Are heart rate zones the same for fat loss and endurance?

Fat loss: Zone 2 burns the highest percentage of fat calories, but total calorie deficit matters most for weight loss
Endurance: Zone 2 builds aerobic capacity—the foundation for all endurance sports

Both benefit from consistent Zone 2 training, but fat loss also requires attention to nutrition.

What if I’m on beta-blockers or other heart medications?

Medications can lower your max HR and alter zone calculations. Consult your doctor before using HR-based training if you’re on cardiac medication. Perceived exertion may be a safer guide.