Heart Rate Training Zones Calculator
Find your personalized cardio training zones by age and resting heart rate. Use it before a workout to set treadmill targets or structure interval sessions across five intensity bands.
About this calculator
Your heart rate training zones are percentage ranges of your maximum heart rate (MHR), which is estimated as 220 − age. The simpler percentage method calculates a zone boundary as (220 − age) × intensity%. The more precise Karvonen method factors in your resting heart rate (HRrest) using the formula: Target HR = ((220 − age − HRrest) × intensity%) + HRrest. This accounts for heart rate reserve (HRR), making it more accurate for fit individuals with low resting heart rates. Most training plans define five zones: Zone 1 (50–60%, recovery), Zone 2 (60–70%, aerobic base), Zone 3 (70–80%, aerobic threshold), Zone 4 (80–90%, lactate threshold), and Zone 5 (90–100%, VO₂ max). Knowing your zones helps you train with purpose rather than guessing effort level.
How to use
Suppose you are 35 years old with a resting heart rate of 60 bpm, and you want to find the upper boundary of Zone 3 (70%) using the Karvonen method. Step 1 – Estimate MHR: 220 − 35 = 185 bpm. Step 2 – Calculate HRR: 185 − 60 = 125 bpm. Step 3 – Apply Karvonen: (125 × 0.70) + 60 = 87.5 + 60 = 147.5 bpm ≈ 148 bpm. Using the simpler percentage method: 185 × 0.70 = 130 bpm. The Karvonen result is higher because it accounts for your fitness level, making it the preferred choice for trained athletes.
Frequently asked questions
What is the difference between the Karvonen method and the standard percentage method for heart rate zones?
The standard percentage method multiplies your estimated maximum heart rate (220 − age) by a target intensity percentage, ignoring your current fitness. The Karvonen method uses your heart rate reserve — the gap between maximum and resting heart rate — to set zones, so a fitter person with a lower resting HR gets higher absolute zone targets. Research shows the Karvonen method correlates more closely with oxygen uptake at any given intensity. For beginners or casual exercisers, the simpler method is adequate; for athletes, Karvonen gives more meaningful boundaries.
How do I measure my resting heart rate accurately for the Karvonen formula?
The most accurate resting heart rate reading is taken first thing in the morning before you get out of bed, after at least five minutes of lying still. Count your pulse for a full 60 seconds or use a heart rate monitor worn overnight. Take readings on three consecutive days and average them, since stress, caffeine, or poor sleep can inflate a single reading. A typical resting HR for adults is 60–80 bpm, while trained endurance athletes often fall between 40–55 bpm.
Why should I train in different heart rate zones instead of always going hard?
Different zones stress different energy systems and physiological adaptations. Zone 2 (aerobic base) builds mitochondrial density and fat-burning efficiency without excessive recovery demand, forming the foundation of endurance fitness. Zones 4 and 5 develop lactate threshold and VO₂ max but require significant recovery time. Polarized training research suggests that elite athletes spend roughly 80% of volume in low zones and 20% in high zones, avoiding the moderate 'junk miles' zone that accumulates fatigue without proportional gains. Mixing zones strategically prevents overtraining and maximizes long-term performance.