Heart Rate Zone Calculator

The Heart Rate Zone Calculator divides your cardiovascular training into five intensity zones based on your maximum heart rate (MHR). Each zone targets a different physiological system — from fat burning at low intensity to peak anaerobic power at high intensity. Knowing your zones helps you structure workouts to match your fitness goals, whether that's endurance, weight loss, or speed.

How to Use This Calculator

1. Enter your age to auto-estimate your maximum heart rate, or enter your measured MHR directly.
2. Optionally enter your resting heart rate for the Karvonen method (more accurate).
3. Click Calculate to see all five heart rate zones in beats per minute (BPM).
4. Use the zones to guide your cardio sessions with a heart rate monitor.

What This Calculator Measures

This calculator outputs five training zones expressed as BPM ranges.

• Zone 1 (50–60% MHR): Recovery and warm-up intensity.
• Zone 2 (60–70% MHR): Aerobic base and fat-burning zone.
• Zone 3 (70–80% MHR): Aerobic endurance and cardiovascular improvement.
• Zone 4 (80–90% MHR): Lactate threshold training and speed development.
• Zone 5 (90–100% MHR): Maximum effort and anaerobic power.

Formula or Logic

The standard formula estimates MHR as 220 minus your age. The Karvonen method refines each zone using Heart Rate Reserve (HRR = MHR − resting HR): Zone BPM = (HRR × zone %) + resting HR. Karvonen zones are more individualized and recommended when resting heart rate is known.

Example Calculations

Example 1: A 30-year-old with estimated MHR of 190 BPM. Zone 2 = 114–133 BPM; Zone 4 = 152–171 BPM.

Example 2: A 45-year-old with MHR 175 and resting HR 60 using Karvonen. HRR = 115. Zone 2 = (115 × 0.6–0.7) + 60 = 129–140 BPM.

Understanding Your Results

Spending most training time in Zones 2–3 builds aerobic capacity efficiently. Zone 4 sessions once or twice per week improve speed and lactate threshold. Zone 5 is reserved for short bursts such as sprints or HIIT intervals.

Common Mistakes to Avoid

• Using the 220 − age formula as absolute truth — individual MHR can vary by ±10–20 BPM.
• Training exclusively in Zone 3, the "grey zone" that's too hard for recovery and too easy for big gains.
• Ignoring Zone 1 and 2 entirely — aerobic base is foundational for all fitness levels.
• Not reassessing zones as fitness improves and resting heart rate decreases.