Aerobic vs Anaerobic Threshold Calculator
Instantly estimate your heart rate training zones using the Karvonen formula to optimise your endurance, fat burning, and athletic performance.
Calculate Your Training Zones
Enter your age and resting heart rate. The calculator uses the scientifically backed Karvonen formula to estimate your Aerobic (Zone 2) and Anaerobic (Zone 4/5) heart rate thresholds.
Heart Rate Zone Calculator
Estimate your personalised aerobic and anaerobic thresholds.
Understanding Your Zones
Key factors that influence your heart rate training
The Karvonen Advantage
Unlike flat percentage formulas, the Karvonen method factors in your Resting Heart Rate, providing a much more personalised and accurate training zone for your specific fitness level.
Aerobic Threshold (AeT)
The upper limit of Zone 2. At this intensity, you can sustain effort for hours, breathe comfortably through your nose, and hold a conversation. It is the primary zone for fat oxidation.
Anaerobic Threshold (AnT)
Also known as the Lactate Threshold. This is the intensity where lactate accumulates in the blood faster than your body can clear it, leading to rapid muscle fatigue and heavy breathing.
External Factors
Remember that heat, humidity, caffeine, stress, and fatigue can elevate your heart rate by 5-15 bpm on any given day. Always listen to your perceived exertion alongside the numbers.
Training Zone Comparison
Generalised benchmarks to help you understand the physiological benefits of training at different heart rate intensities.
| Zone | Intensity (% of HRR) | Primary Fuel Source | Key Benefit |
|---|---|---|---|
| Recovery | 50% – 60% | Fat | Active recovery, blood flow |
| Aerobic (AeT) | 60% – 75% | Fat & Carbohydrates | Mitochondrial density, endurance base |
| Tempo | 75% – 80% | Carbohydrates | Muscular endurance, aerobic power |
| Anaerobic (AnT) | 80% – 90% | Carbohydrates (Glycogen) | Lactate clearance, VO2 max improvement |
| Neuromuscular | 90% – 100% | Phosphocreatine | Top speed, anaerobic capacity |
Threshold Calculator FAQ
Answers to the most frequently asked questions about heart rate training zones and threshold calculations.
The aerobic threshold (AeT) is the intensity at which your body primarily uses oxygen to produce energy, allowing for sustained, conversational effort. The anaerobic threshold (AnT), or lactate threshold, is the point where lactic acid accumulates in the blood faster than it can be cleared, leading to rapid fatigue and heavy breathing.
The Karvonen formula calculates your target heart rate using your Heart Rate Reserve (HRR). HRR is your Maximum Heart Rate minus your Resting Heart Rate. The formula is: (HRR × Target Intensity Percentage) + Resting Heart Rate. This method is more accurate than using a flat percentage of your maximum heart rate.
Fat burning is most efficient in Zone 2, which aligns closely with your Aerobic Threshold (typically 60% to 75% of your Heart Rate Reserve). At this intensity, your body can effectively utilise fat as its primary fuel source without accumulating fatigue.
The ‘220 minus age’ formula is a widely used population average, but it can vary by ±10-15 bpm for individuals. For highly accurate training zones, consider getting a professionally administered VO2 max or lactate threshold test, or use a known max HR from a recent maximal effort test.
Yes, the Karvonen formula is sport-agnostic and applies to any cardiovascular activity. However, note that your maximum heart rate may be slightly lower (by 5-10 bpm) in cycling or swimming compared to running due to differences in muscle mass recruitment and body position.