Heart Rate Calculator UK 2025 | Target Heart Rate Zones for Exercise
Free UK Heart Rate Zone Calculator 2025. Calculate your maximum heart rate and target training zones using the Karvonen method.
Last updated: February 2026
Heart Rate Zone Calculator
Calculate your maximum heart rate and target training zones for optimal exercise intensity based on NHS and British Heart Foundation guidelines.
Maximum Heart Rate
Your Training Zones
Understanding Heart Rate Zones
Heart rate zones are ranges of heartbeats per minute that correspond to different exercise intensities. Training in specific zones helps you achieve different fitness goals, from fat burning to improving cardiovascular endurance to building speed and power.
| Zone | Intensity | % Max HR | Primary Benefit | Feel |
|---|---|---|---|---|
| Zone 1 | Recovery | 50-60% | Warm-up, active recovery | Very light, can hold conversation easily |
| Zone 2 | Endurance | 60-70% | Fat burning, aerobic base | Light, can talk in full sentences |
| Zone 3 | Aerobic | 70-80% | Cardiovascular fitness | Moderate, can speak but somewhat breathless |
| Zone 4 | Threshold | 80-90% | Lactate threshold, speed | Hard, can only say a few words |
| Zone 5 | Maximum | 90-100% | Maximum power, speed | Maximum effort, cannot speak |
Maximum Heart Rate Formulas
Your maximum heart rate (MHR) is the highest number of beats per minute your heart can achieve during maximum physical exertion. Several formulas exist to estimate this value.
Traditional Formula (Most Common)
Simple and widely used, though may underestimate MHR in older adults
Tanaka Formula (More Accurate)
Research-based formula, often more accurate for people over 40
Karvonen Formula (Most Personalised)
Where Heart Rate Reserve = Max HR - Resting HR. Accounts for individual fitness level.
Understanding Resting Heart Rate
Your resting heart rate (RHR) is the number of times your heart beats per minute when you're completely at rest. It's a key indicator of cardiovascular fitness and overall heart health.
| Resting Heart Rate | Fitness Level | Notes |
|---|---|---|
| 40-50 bpm | Excellent (Athletic) | Common in elite endurance athletes |
| 51-60 bpm | Very Good | Regular exercisers, good fitness |
| 61-70 bpm | Good | Healthy average for active adults |
| 71-80 bpm | Average | Typical for general population |
| 81-100 bpm | Below Average | May indicate poor fitness or stress |
How to Measure Your Resting Heart Rate
- Timing: Measure first thing in the morning before getting out of bed, or after sitting quietly for at least 5 minutes
- Location: Place your index and middle fingers on your wrist (below the thumb) or on your neck (beside the windpipe)
- Counting: Count the number of beats for 60 seconds, or count for 15 seconds and multiply by 4
- Accuracy: Take readings on 3-5 different days and calculate the average for best accuracy
- Avoid: Don't measure after caffeine, alcohol, stress, or exercise - these elevate heart rate
Training in Each Heart Rate Zone
Zone 1: Recovery (50-60% Max HR)
Use this zone for warm-ups, cool-downs, and active recovery days. It helps promote blood flow and recovery without adding training stress. Walking, gentle yoga, or very light cycling are examples.
Zone 2: Endurance/Fat Burning (60-70% Max HR)
The foundation of aerobic fitness. Training here improves your body's ability to use fat as fuel and builds cardiovascular base. Most of your training (70-80%) should be in this zone. Examples: easy jogging, steady cycling, swimming laps.
Zone 3: Aerobic (70-80% Max HR)
Improves cardiovascular efficiency and stamina. You can sustain this intensity for extended periods but will feel the effort. This is a "tempo" pace - harder than easy but not race pace. Good for improving fitness without extreme stress.
Zone 4: Threshold (80-90% Max HR)
Training at or near your lactate threshold. This zone improves your ability to sustain harder efforts and is crucial for competitive performance. However, it's demanding and requires adequate recovery. Use sparingly - perhaps 1-2 sessions per week.
Zone 5: Maximum (90-100% Max HR)
Near-maximal to maximal effort. Only sustainable for short bursts (30 seconds to a few minutes). Used for high-intensity interval training (HIIT) and improving peak power and speed. Very demanding on the body - use only when well-rested and recovered.
Tips for Heart Rate Training
Use a Heart Rate Monitor
Chest straps are most accurate, but modern wrist-based monitors (smartwatches) are convenient and reasonably accurate for steady-state exercise. Check readings occasionally against manual pulse.
Don't Ignore RPE
Rate of Perceived Exertion (how hard it feels) is valuable alongside HR data. Some days your heart rate may be elevated due to stress, caffeine, or poor sleep - adjust intensity based on how you feel.
Build Your Base First
Spend 6-8 weeks building aerobic fitness in Zones 1-2 before adding higher intensity work. This creates the foundation for harder training and reduces injury risk.
Track Progress
Over time, you should be able to run/cycle faster at the same heart rate - this is called cardiac drift reduction and indicates improving fitness. Track your pace at Zone 2 heart rate.
Warm Up Properly
Start every session with 5-10 minutes in Zone 1. This gradually increases heart rate, warms muscles, and prepares your cardiovascular system for harder effort.
Cool Down Gradually
Don't stop suddenly from high-intensity exercise. Gradually reduce to Zone 1 for 5-10 minutes to help your heart rate return to normal and promote recovery.
Frequently Asked Questions
The simplest formula is 220 minus your age. For example, a 40-year-old has an estimated maximum heart rate of 180 bpm. More accurate formulas like Tanaka (208 - 0.7 x age) exist but the 220-age method is widely used for general fitness. For the most accurate result, a supervised maximal exercise test can be performed by a sports scientist or cardiologist.
The 'fat burning zone' is typically 60-70% of your maximum heart rate (Zone 2). While a higher percentage of calories burned in this zone come from fat (around 60%), you actually burn more total calories and more total fat at higher intensities due to the greater energy expenditure. The best zone for weight loss is whichever you can sustain consistently - for most people, that's Zone 2.
According to the NHS, a normal resting heart rate for adults is 60-100 bpm. Well-trained endurance athletes may have resting heart rates of 40-60 bpm due to their highly efficient cardiovascular systems. A lower resting heart rate generally indicates better cardiovascular fitness. If your resting heart rate is consistently above 100 bpm or below 50 bpm (without being athletic), consult your GP.
The Karvonen formula calculates target heart rate using your Heart Rate Reserve (HRR), which is your maximum heart rate minus your resting heart rate. The formula is: Target HR = Resting HR + (HRR x intensity %). This method is more personalised because it accounts for your individual fitness level via your resting heart rate. Someone with a lower resting heart rate will have different zone values than someone of the same age with a higher resting heart rate.
It depends on your goals. For general health and weight loss, Zone 2 (60-70%) is excellent - it builds aerobic base, burns fat, and is sustainable for longer durations. For improving cardiovascular fitness, include some Zone 3 (70-80%). For competitive performance, periodically train in Zone 4-5. Most experts recommend 80% of training in Zones 1-2 and 20% in higher zones to avoid overtraining.
The most accurate time is first thing in the morning before getting out of bed. Place two fingers on your wrist (radial artery) just below your thumb, or on your neck (carotid artery) beside your windpipe. Count the beats for 60 seconds, or count for 15 seconds and multiply by 4. Take readings over 3-5 days and average them for best accuracy. Avoid measuring after caffeine, stress, or exercise.
Several factors can elevate heart rate: dehydration, caffeine, poor sleep, stress, heat/humidity, illness, or being new to exercise. Cardiac drift (heart rate increasing during prolonged exercise even at constant effort) is also normal due to dehydration and heat buildup. If your heart rate is consistently and significantly higher than expected, or you experience symptoms like dizziness or chest pain, consult your GP.
For healthy, fit individuals, brief periods in Zone 5 during interval training can be safe and beneficial. However, you should only attempt high-intensity training after building a solid aerobic base, always warm up thoroughly, and ensure adequate recovery between hard sessions. If you're over 40, new to exercise, or have any heart conditions, consult your GP before high-intensity training. Never push through chest pain, dizziness, or unusual symptoms.
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Last updated: February 2026 | Reviewed for accuracy against NHS and British Heart Foundation guidelines
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