Heart Rate Cardio Zones Calculator
Estimate your training zones for running, cycling, rowing, and other endurance workouts.
Why cardio zones matter
A cardio zone is a heart-rate intensity band that helps you train with purpose instead of guessing. Rather than running every workout at a medium-hard pace, zones let you distribute effort across easy, moderate, threshold, and high-intensity work.
This approach improves endurance, supports recovery, and reduces burnout. It also makes your workouts easier to track over time, especially when combined with a fitness watch or chest strap.
The 5 common heart-rate zones
Zone 1 (50–60%): Recovery
Very easy effort. Great for warm-ups, cool-downs, and recovery days. Breathing should feel relaxed and conversational.
Zone 2 (60–70%): Aerobic base
Easy but steady. This is the foundation of endurance training. Most long-term cardio progress is built here.
Zone 3 (70–80%): Tempo
Moderate effort that challenges your aerobic engine. Useful in controlled doses for fitness development and race preparation.
Zone 4 (80–90%): Threshold
Hard effort near your lactate threshold. Improves your ability to sustain a faster pace for longer periods.
Zone 5 (90–100%): VO₂ max / sprint effort
Very hard intensity for short intervals. Builds top-end performance but requires full recovery and careful planning.
How this calculator works
The calculator uses one of two methods:
- % Max HR method: Uses percentages of your maximum heart rate.
- Karvonen method: Uses heart-rate reserve (Max HR − Resting HR) for more individualized targets.
If you provide resting heart rate, you'll see both methods. If you provide a measured max heart rate from a supervised test or hard field effort, that value overrides any formula estimate.
How to use your zones in a weekly plan
- Most sessions: Zone 1–2 (easy volume).
- 1–2 sessions/week: Zone 3–4 (structured quality).
- Occasional short intervals: Zone 5.
- After hard days: return to Zone 1 recovery work.
Common mistakes to avoid
- Doing every session too hard ("always Zone 3–4").
- Ignoring sleep, hydration, and recovery stress.
- Relying only on watch-based optical HR during intervals (a chest strap is often more accurate).
- Not adjusting zones as fitness changes over time.
Final note
Cardio zones are a practical guide, not a rigid rule. Use them with perceived effort, pace/power, and common sense. If you have cardiovascular or metabolic conditions, consult a licensed healthcare professional before beginning or changing your training program.