Heart Rate Zone Calculator
Calculate your five heart rate training zones from your maximum heart rate for targeted cardio training.
Training in the right zone makes a real difference in outcomes. Most recreational runners and gym-goers spend nearly all their cardio time in zones 3–4, which builds some aerobic capacity but burns out faster and makes recovery harder. Zone 2 training, easy, conversational pace, is what builds the aerobic base that makes everything else better. Zone 5 intervals are what raise the ceiling.
Zone 2 training (60–70% of max HR) builds the aerobic base, burns fat, and enhances recovery. Most people do too little of it. Polarized training, mostly zone 2 with some zone 5, is what elite endurance athletes use and what the research increasingly supports.
The five training zones
Zone 1 (50–60%): Active recovery. Very light effort, a walk or gentle spin. Promotes recovery without adding training stress. Zone 2 (60–70%): Aerobic base building. You can hold a full conversation. Fat is the primary fuel. The zone most people underutilize. Zone 3 (70–80%): Aerobic tempo. You can speak in short sentences. Improves efficiency but generates more fatigue than zone 2. Zone 4 (80–90%): Lactate threshold. Hard effort, can only say a few words. Builds speed and power but requires longer recovery. Zone 5 (90–100%): Maximal effort. Sprints and intervals. Raises VO2 max ceiling but very demanding, typically 5–10% of weekly training volume.
% of max HR vs Karvonen method
The simple percentage method calculates zones as a percentage of your maximum heart rate. The Karvonen (heart rate reserve) method uses heart rate reserve, the range between resting and maximum HR. Karvonen zones: Target HR = Resting HR + (Max HR − Resting HR) × zone percentage. Karvonen produces slightly different (often higher absolute) zone boundaries and is considered more accurate for individuals with very low or very high resting heart rates.
Estimating max heart rate
The classic formula 220 − age is a population average with significant individual variation (±10–20 bpm). Better alternatives: 208 − (0.7 × age) (Tanaka formula, more accurate for older adults) or direct measurement via a true maximal effort test. If you have a measured max HR from a stress test or hard race effort, use that, it's always more accurate than any formula.
Frequently asked questions
How do I know what zone I'm in during exercise?
A heart rate monitor (chest strap or optical wristband). Chest straps are more accurate, especially during high-intensity intervals where optical sensors lag. Most fitness watches display real-time heart rate and zone. Alternatively, the "talk test", whether you can hold a conversation, approximates zone 2/3 boundary.
What percentage of training should be in each zone?
For endurance athletes, the polarized model suggests approximately 80% in zones 1–2, 10% in zone 3, and 10% in zones 4–5. For recreational fitness, 60–70% zone 2, 20–30% zone 3, and 5–10% zone 4–5 is a practical starting point. The most common mistake is spending too much time in zone 3, moderate effort that's harder than recovery but not as productive as true base or intensity work.