Enter your age and resting heart rate to find your 5 training zones — from easy recovery to all-out effort — using the Karvonen formula.
Your 5 training zones
Zones use the Karvonen formula: Target HR = ((Max HR − Resting HR) × % Intensity) + Resting HR. More accurate than simple percentage methods because it accounts for your fitness level. Exercise carries inherent risks including cardiac events. By using these training zones, you assume all associated risks. Stop immediately if you feel chest pain, dizziness, or shortness of breath. Consult a physician before beginning any exercise program.
Heart rate zones divide exercise intensity into five ranges, each producing different adaptations. Zone 2 (60–70%) builds aerobic base and burns fat efficiently. Zone 4 (80–90%) improves lactate threshold. Zone 5 (90–100%) builds maximum power but can only be sustained briefly.
Most recreational exercisers spend too much time in Zone 3 — hard enough to feel tough, but not optimal for either fat burning or peak performance. Elite endurance athletes follow a "polarized" model: 80% of training in Zones 1–2, and 20% in Zones 4–5.
The simple method (max HR × percentage) ignores fitness level. Two 30-year-olds could have resting heart rates of 55 bpm (trained runner) vs. 80 bpm (sedentary). The Karvonen formula uses heart rate reserve (max HR minus resting HR), giving personalized zones that reflect actual cardiovascular fitness.
Measure your pulse first thing in the morning before getting out of bed or having coffee. Count beats for 60 seconds. Average 3–5 mornings for accuracy. A fitness tracker can also measure it during sleep.
It provides a rough estimate with ±10–12 bpm individual variation. For precise max heart rate, a graded exercise test is the gold standard. For most people, the estimate is sufficient for zone-based training.
Zone 2 (60–70%) uses the highest percentage of fat as fuel. However, higher zones burn more total calories per minute. For weight loss, total calorie expenditure matters more than the fuel source. Zone 2 is excellent for longer, sustainable sessions.
For general fitness: 80% in Zones 1–2 (easy, conversational pace), 20% in Zones 4–5 (intervals, sprints). This polarized approach consistently outperforms training at constant moderate intensity.